This is a list of English words which are commonly misused. It is meant to include only words whose misuse is deprecated by most usage writers, editors, and other professional linguists of Standard English. It is possible that some of the meanings marked non-standard may pass into Standard English in the future, but at this time all of the following non-standard phrases are likely to be marked as incorrect by English teachers or changed by editors if used in a work submitted for publication. Some of the examples are homonyms or pairs of similarly spelled words which are often confused.
The words listed below are frequently used in ways that major English dictionaries do not condone in any definition. See list of English words with disputed usage for words that are used in ways that are deprecated by some usage writers but are condoned by some dictionaries. There may be regional variations in grammar, spelling, and word-use, especially between different English-speaking countries. Such differences are not seen as incorrect once they have gained widespread acceptance in a particular country.
abdicate, abrogate, and arrogate. To abdicate is to resign from the throne, or more loosely to cast off a responsibility. To abrogate is to repeal a law or abolish an arrangement. To arrogate is to attempt to take on a right or responsibility to which one is not entitled.
Standard: Edward VIII abdicated the throne of the United Kingdom.
Standard: Henry VIII abrogated Welsh customary law.
Non-standard: John abrogated all responsibility for the catering arrangements (should be "abdicated").
Non-standard: You should not abrogate to yourself the whole honour of the President's visit (should be "arrogate").
accept and except. While they sound similar (or even identical), except is a preposition that means "apart from", while accept is a verb that means "agree with", "take in", or "receive". Except is also occasionally used as a verb, meaning to take out or to leave out.
Standard: We accept all major credit cards, except Diners Club.
Standard: Men are fools... present company excepted! (Which means, "present company excluded")
Non-standard: I had trouble making friends with them; I never felt excepted.
Non-standard: We all went swimming, accept for Jack.
acute and chronic. Acute means "sharp", as an acute illness is one that rapidly worsens and reaches a crisis. A chronic illness may also be a severe one, but it is long-lasting or lingering.
Standard: She was treated with epinephrine during an acute asthma attack.
Standard: It is not a terminal illness, but it does cause chronic pain.
Non-standard: I have suffered from acute asthma for twenty years.
Non-standard: I just started feeling this chronic pain in my back.
adverse and averse. Adverse means unfavorable, contrary or hostile. Averse means having a strong feeling of opposition, antipathy, or repugnance. Merriam-Webster notes that adverse is commonly used as an attributive adjective (before the noun), while "averse" is rarely used in this situation.
Standard: They sailed despite adverse weather conditions.
Standard: He was averse to taking his medicine.
Non-standard: He is not adverse to having a drink now and then.
affect and effect. The verb affect means "to influence something", and the noun effect means "the result of". Effect can also be a verb that means "to cause [something] to be", while affect as a noun has technical meanings in psychology, music, and aesthetic theory: an emotion or subjectively experienced feeling. A device to remember when trying to decide which is the right choice: If something affects you it usually has an effect on you.
Standard: This poem affected me so much that I cried.
Standard: Temperature has an effect on reaction spontaneity.
Standard: The dynamite effected the wall's collapse.
Standard: He seemed completely devoid of affect.
Non-standard: The rain effected our plans for the day.
Non-standard: We tried appeasing the rain gods, but to no affect.
Non-standard: An IOC spokesman told Press Association Sport: "We were aware that FIFA might consider changing the dates for the 2022 World Cup. We are confident that FIFA will discuss the dates with us so as to co-ordinate them and avoid any affect on the Winter Games."
Non-standard: Some neighbors complain about Romney's new presidential entourage—including dozens of Secret Service agents who now guard the candidate 24 hours a day—and its affect on their quiet street.
aggravate and mitigate. Aggravate means "to make worse". Mitigate means "to make less bad" (see also mitigate versus militate, below). "Mitigating factor" refers to something that affects someone's case by lessening the degree of blame, not anything that has any effect at all.
algorithm and logarithm. An algorithm is a step-by-step procedure, usually for calculation, the processing of data, or choosing among alternatives. The logarithm of a number is the power (i.e. exponent) to which a specified base must be raised to produce that number.
Standard: The board of directors developed an algorithm for choosing the company's new president from among the remaining candidates.
Standard: Using a base of 2 the logarithm of 32 is 5, because 25 equals 32.
a lot and allot. A lot means many; allot means to distribute something.
allusion, illusion, and hallucination. An allusion is an indirect or metaphorical reference to something; an illusion is a false picture of something that is there; a hallucination is the seeing of something that is not there.
alternately and alternatively. Alternately is an adverb that means in turn; one after the other. Alternatively is an adverb that means on the other hand; one or the other.
Standard: We alternately spun the wheel in the game.
Standard: You can choose a large bookcase or, alternatively, you can buy two small ones.
appraise and apprise. To appraise is to assess or value something; to apprise is to teach or inform.
Standard: His performance was appraised very positively.
Standard: I lost no time in apprising her of the situation.
Non-standard: Has he been appraised of the fact?
are and our. Are refers to the 2nd person singular present and 1st, 2nd, 3rd person plural present of the verb be. Our means "belonging to us."
Standard: Are you coming to our house after the show?
Non-standard: Are family has been trying to save money because of the country's current economic situation.
assume: to suppose to be true, especially without proof, and presume: to take for granted as being true in the absence of proof to the contrary. Presume can also mean "take excessive liberties", as in the adjective form "presumptuous".
Standard: They had assumed that they were alone, so they were surprised when they heard a third voice join their song.
Standard: Doctor Livingstone, I presume?
assure, ensure, and insure. In American English, to assure is purely to intend to give the listener confidence, to ensure is to make certain of, and to insure is to purchase insurance. The only difference with British English is that "assure" can be used instead of "insure", particularly in the context of life insurance/assurance.
Standard: I assure you that I will have your car washed by the time you return.
Standard: When you mow the lawn, ensure there are no foreign objects in the grass.
Standard: I plan to purchase the collision policy when I insure my car.
Standard: I already have more than enough life assurance.
Non-standard: His actions insured that the attacking army would fail.
bemused. To be bemused is to be perplexed or bewildered; however, it is commonly used incorrectly in place of amused.
bifurcate. Bifurcate means to segregate or divide into two parts. It is not a stand-in for 'more than one.'
bisect and dissect. Bisect means "to cut into two"; dissect means "to cut apart", both literally and figuratively. Disect is an archaic word meaning "to separate by cutting", but has not been in common use since the 17th century.
Standard: The Americas are bisected by the Panama canal.
Standard: She dissected Smith's dissertation, pointing out scores of errors.
Standard: We dissected the eye of a bull in biology class today.
Non-standard: We bisected the eye of a bull in biology class today.
breath and breathe. A breath (noun) is the air that is inhaled or exhaled from the lungs. To breathe (verb) is the act of inhaling or exhaling.
cache and cachet. A cache (IPA: /kæʃ/) is a storage place from which items may be quickly retrieved. A cachet (IPA: /kæˈʃeɪ/) is a seal or mark, such as a wax seal on an envelope or a mark of authenticity on a product (usually used figuratively to mean "marked by excellence, distinction or superiority").
Standard: The pirates buried a cache of jewels near the coast.
Standard: Living in New York City definitely has a certain cachet.
Non-standard: If your web browser is running slowly, try emptying the cachet.
can't and cant. Can't is a contraction of cannot. Cant has a number of different meanings, including a slope or slant, or a kind of slang or jargon spoken by a particular group of people. "Canting arms" is a coat-of-arms that represents meaning of the bearer's surname.
Standard: I can't understand the dialogue in this book because it is written in cant.
Non-standard: I cant swim; I have never taken lessons.
complementary and complimentary. Things or people that go together well are complementary (i.e., they complete each other); complimentary describes to an item given without charge (considered a 'gift'), usually in addition to a product or service that may have been purchased. It also describes praise given to someone or something.
Standard: Exercise, nutrition, and medical care are complementary factors in good health.
Standard: The motel provides a complimentary breakfast to overnight guests.
Standard: Jane was complimentary about the new couch, which she said complements the drapes and carpet.
Similarly, a complement is an accessory, while a compliment is a statement of admiration.
complacency and complaisance. Complacency means self-satisfaction especially when accompanied by unawareness of actual dangers or deficiencies. Complaisance means the willingness to comply with the wishes of others.
contiguous, continual, and continuous. Contiguous means "touching" or "adjoining in space"; continual means "repeated in rapid succession"; continuous means "uninterrupted" (in time or space).
Standard: Alaska is not one of the forty-eight contiguous states.
Standard: The field was surrounded by a continuous fence.
Standard: The continuous murmur of the stream.
Standard: His continual interruptions are very irritating.
contingent and contingency. As a noun, a contingent is a representative group; a contingency is a possible event.
Standard: The explorers were prepared for every contingency.
Standard: He was a member of the California contingent at the convention.
Non-standard: He was greeted by a contingency from the school board.
crotch and crutch. A crotch is an area where something branches or forks off in two directions, or the area on a person's body where the legs fork from the trunk (commonly interchanged with 'groin'). A crutch is a device that assists motion, especially one that sits under the armpit. It is also used metaphorically for something that supports, often negatively to imply a dependency on something that would not be needed by a healthy person.
decimate and devastate. To decimate is to damage or remove a large portion of something, often one-tenth (latin decem=tenth); to devastate is to destroy or ruin most of something.
defuse and diffuse. To defuse is to remove the fuse from a bomb, or in general to render a situation less dangerous, whereas to diffuse is to disperse randomly. Diffuse can also be used as an adjective, meaning "not concentrated".
Standard: Bill's face turned red at Joe's tactless remark to the Kennel Club meeting, but Clarice defused the situation by turning it into a joke. "Not that even a Dachshund would stoop so low, of course!" she quipped.
Standard: The speaker droned on, his words like a powerful sleeping gas slowly diffusing through the stuffy air of the auditorium.
Standard: The spotlights went dark, leaving the scene lit only by the diffuse glow of the lanterns.
Non-standard: Houston was aware it was happening and worked to diffuse the campaign late in the process.
Non-standard: A government agency long associated with efforts to mediate and diffuse tense situations in communities helped organize rallies over the killing of Florida teen Trayvon Martin last year, a conservative leaning legal advocacy group claims.
desert and dessert. A desert is a barren or uninhabited place; an older meaning of the word is "what one deserves", as in the idiom just deserts. A dessert is the last course of a meal.
disburse and disperse. Disburse means "to give out", especially money. Disperse means "to scatter".
discreet and discrete. Discreet means "circumspect". Discrete means "having separate parts", as opposed to contiguous.
disinterested and uninterested. To be disinterested in something means to not be biased about something (i.e. to have no personal stake in a particular side of an issue). To be uninterested means to not be interested in or intrigued by something.
Standard: As their good friend, I tried to mediate their argument in a disinterested manner so as not to anger either.
Standard: Though his initial reaction suggested otherwise, he maintains that he remains uninterested in the business proposition.
Non-standard: The key to attracting a member of the opposite sex is to balance between giving attention to him or her and appearing disinterested.
economic and economical. Economic means "having to do with the economy". Economical means "financially prudent, frugal" and also figuratively in the sense "sparing use" (of time, language, etc.)
Standard: Buying in bulk can often be the most economical choice.
Standard: The actor should be economical in his use of movement.
Standard: He attended the School of Economic and Business Sciences.
Non-standard: Leading economical indicators suggest that a recession may be on the horizon.
Non-standard: The actor should be economic in his use of movement.
e.g. and i.e. The abbreviation e.g. stands for the Latin exempli gratiā "for example", and should be used when the example(s) given are just one or a few of many. The abbreviation i.e. stands for the Latin id est "that is", and is used to give the only example(s) or to otherwise qualify the statement just made.
Standard: A Briton is a British citizen, e.g. John Lennon.
Standard: Tolkien's The Hobbit is named after its protagonist, i.e., Bilbo Baggins.
Non-standard: A Briton is a British citizen, i.e., Paul McCartney (at the last count, there were about 60 million Britons—Sir Paul is far from being the only one)
emigration and immigration. Emigration is the process of leaving a country; immigration is the process of arriving in a country—in both cases, indefinitely.
Standard: Ethnic communities, such as Little Italy, were created by people emigrating from their home countries.
eminent, preeminent, imminent, and immanent. Eminent, originally meaning "emerging", means "illustrious or highly-regarded". Preeminent means "most highly-regarded". Imminent means "about to occur". Immanent (less common than the other two, and often theological) means "indwelling, pervading".
Standard: The eminent doctor Jones testified on behalf of the defence.
Standard: Rumours that war was imminent soon spread through the population.
Standard: God's grace is immanent throughout the entire creation.
eponymous is used to describe something which gives its name to something else, not something which receives the name of something else.
Standard: Frank, the eponymous owner of Frank's Bistro, prepares all meals in a spotless kitchen.
Non-standard: Frank maintains an eponymous restaurant, Frank's Bistro.
exacerbate and exasperate. Exacerbate means "to make worse". Exasperate means "to exhaust", usually someone's patience.
Standard: Treatment by untrained personnel can exacerbate injuries.
Standard: Do not let Jack talk to the state trooper; he is tactless and will just exasperate her.
expedient and expeditious. Expedient means "to do conveniently or quickly, but possibly improperly". Expeditious means "done efficiently", and does not carry any negative connotation.
Standard: The chef's expedient solution was to microwave the undercooked hamburger.
Standard: The chef's expeditious solution was to cook a new hamburger.
flesh and flush. To flesh out is to add flesh to a skeleton, or metaphorically to add substance to an incomplete rendering. To flush out is to cause game fowl to take to flight, or to frighten any quarry from a place of concealment.
Standard: The forensic pathologist will flesh out the skull with clay.
Standard: The beaters flushed out the game with drums and torches.
Non-standard: This outline is incomplete and must be flushed out.
flounder and founder. To flounder is to be clumsy, confused, indecisive, as if flopping about like a fish out of water (a flounder being a kind of fish). To founder is to fill with water and sink (or, figuratively, to fail).
Non-standard: The ship is damaged and may flounder.
flout and flaunt. One flouts a rule or law by flagrantly ignoring it. One flaunts something by showing it off.
Standard: If you have it, flaunt it.
Standard: He continually flouted the speed limit.
Standard: The diplomat's son flaunted his ability to flout the speed limit.
Non-standard: If you have it, flout it.
Non-standard: He continually flaunted the speed limit.
hay and straw. Hay is a grassy plant used as animal fodder. Straw is the dry stalk of a cereal plant (e.g., barley, oats, rice, rye), after the grain or seed has been removed; it is used to line an animal's stall or for insulation.
hang. To hang something or someone in the present tense, one uses the same form. In the past, however, pictures are hung or hanged.
hangar and hanger. The aeroplane is in the hangar; the coat is on the hanger.
hear and here. To "hear" is to detect a sound with one's ears. "Here" refers to one's immediate location.
hoard and horde. A hoard is a store or accumulation of things. A horde is a large group of people.
Standard: A horde of shoppers lined up to be the first to buy the new gizmo.
Standard: He has a hoard of discontinued rare cards.
Non-standard: Do not horde the candy, share it.
Non-standard: The hoard charged when the horns sounded.
imply and infer. Something is implied if it is a suggestion intended by the person speaking, whereas a conclusion is inferred if it is reached by the person listening.
Standard: When Tony told me he had no money, he was implying that I should give him some.
Standard: When Tony told me he had no money, I inferred that I should give him some.
Non-standard: When Tony told me he had no money, he was inferring that I should give him some.
inherent and inherit. A part inherent in X is logically inseparable from X. To inherit is a verb, meaning "pass down a generation".
Standard: Risk is inherent in the stock market.
Standard: The next president inherits a legacy of mistrust and fear.
Non-standard: There is violence inherit in the system.
Standard: It's been nice getting to meet you. (it has been)
Standard: My cell phone has poor reception because its antenna is broken.
Non-standard: Its good to be the king.
Non-standard: The bicycle tire had lost all of it's pressure.
irony. Something is ironic if it is the opposite of what is appropriate, expected, or fitting.
Standard: It is ironic that the center for the handicapped has no wheelchair ramp.
Standard: It is ironic that Alanis Morissette wrote a song called "Ironic" with many examples, not one of which is actually ironic.
Non-standard: It is ironic that George W Bush is right-handed and Republican while Bill Clinton is left-handed and Democratic.
Non-standard: It is raining on our wedding day! Is it not ironic?
isle and aisle. An isle is an island. An aisle is corridor through which one may pass from one place to another.
Standard: He came from a small isle in the Caribbean.
Standard: The coffee is down the third aisle on the left.
jive and jibe. Jive is hepcat patois or deception. Jibe is to be in accord with.
Standard: Don't give me that same old jive.
Standard: Your report doesn't jibe with the facts.
Non-standard: Your report doesn't jive with the facts.
lay (lay, laid, laid, laying, lays) and lie (lie, lay, lain, lying, lies) are often used synonymously. Lay is a transitive verb, meaning that it takes an object. "To lay something" means to place something. Lie, on the other hand, is intransitive and means to recline. The distinction between these related verbs is further blurred by the fact that the past tense of lie is lay. An easy rule of thumb is to replace the words with sit and set. If sit makes sense (e.g. sit down) then lie should be used (lie down). If the sentence works with set (e.g. set the book on the table) then lay should be used (lay the book on the table). A layoff is never a lieoff or lyoff. (To lie can also mean "to not tell the truth" – but in that case, the past tense is lied.)
Standard: I lay my husband's work clothes out for him every morning. Yesterday, I decided to see if he paid attention to what I was doing, so I laid out one white sock and one black. He did not notice!
Standard: You should not lie down right after eating a large meal. Yesterday, I lay on my bed for half an hour after dinner, and suffered indigestion as a result. My wife saw me lying there and made me get up; she told me that if I had waited for a couple of hours I could have lain down in perfect comfort.
Standard: You lied to me; there is no hidden chamber!
Non-standard: Since the gunmen remained at large for more than four months after the shooting, Nellum often laid in bed wondering who his assailants were and whether they might come after him again.
Non-standard: "It could be easy for those guys to lay down. After I left, they could have just laid down."
Non-standard: Yueyue laid motionless in the street for 10 minutes until Chen Xianmei, a 58-year-old woman who collects trash for a living, passed by.
Non-standard: Schaub laid on the ground for a while before being taken off the field.
Non-standard: Jurors squirmed Monday as a Massachusetts pathologist detailed the wounds inflicted on the 19 bodies prosecutors have lain at the feet of reputed Boston mob boss James "Whitey" Bulger.
Non-standard: For two days he laid in bed, locked in a daze.
Non-standard: Is this bed comfortable when you lay on it? (Should be lie)
Non-standard: Yesterday I lied down in my office during the lunch hour. (Should be lay)
Non-standard: There was no reason for him to have laid down in the middle of the path, it unnerved me to see him laying there saying nothing. (Should be "have lain down" and "him lying there")
Non-standard: Lie the baby down, and change his diaper (Should be lay, as lie is intransitive)
Non-standard: I am going to lay out in the sun and work on my tan. (Should be lie. In general, the term lay out when referring to sunbathing is always non-standard usage.)
Non-standard: Sorry, I lay about our appointment yesterday. (Should be lied)
Non-standard: You should not lay down right after eating a large meal. Yesterday, I lied on my bed for half an hour after dinner, and suffered indigestion as a result. My wife saw me laying there and made me get up; she told me that if I had waited for a couple of hours I could have lied down in perfect comfort. (Should be lie, lay, lying and lain)
levee and levy. A levee is a structure built along a river to raise the height of its banks, thereby preventing nearby land from flooding (see: dike). To levy is to impose (1) a tax, fine or other assessment, or (2) a military draft; as a noun, a levy is an assessment or army thus gathered. The two words share a common root, but they are not considered interchangeable in Standard English. Because they are homophones, misuse is usually only apparent when observed in writing.
Standard: The Netherlands is well known for its elaborate system of levees.
Standard: This statute allows the state to levy a 3% tax.
Non-standard: Recent storms have weakened the levy.
loathe and loath or loth: Loathe is a verb meaning "to strongly dislike", and loath (or loth) is an adjective meaning "unwilling" or "reluctant".
Standard: I loathe arrogant people.
Standard: I was loath to concede defeat.
Standard: I was loth to submit to a body-cavity search until I saw who would be administering it.
Non-standard: Colangelo and Krzyzewski are loathe to break the players up into categories, but essentially, that's what is in place.
Non-standard: Which is why the Panthers were loathe to give him a guaranteed contract.
lose and loose. Lose can mean "fail to win", "misplace", or "cease to be in possession". Loose can mean the opposite of tight, or the opposite of tighten. Lose is often misspelled loose, likely because lose has an irregular rhyme for the way it is spelled: it is more common for words ending -ose to rhyme -əʊz, like nose, or rose, but lose rhymes -uːz, like news or confuse. This may cause poor spellers to guess the correct spelling should match another -uːz rhyming word like choose, although choose is itself also an exception to the regular rhyme for words ending -oose (typically such words, including loose, rhyme -uːs, like goose or caboose).
Standard: We cannot afford to lose customers to our competitors.
Standard: A screw is loose and I need a screwdriver to tighten it.
Non-standard: If the team cannot score any points, they will loose the game.
macerate, marinate, and marinade. (From post-classical Latin marina brine, short for classical Latin aqua marina sea water.) In Standard English, marinade is a noun and not a verb; marinate is the verb. Macerate means "to soften by steeping in a liquid" and in culinary terminology is used for non-protein items, specifically fruit. The word macerate is also used in science "to soften bone, rock etc. in a liquid".
Standard: The meat will taste better if you marinate it in olive oil before cooking.
Standard: Prepare the marinade by mixing vinegar and soy sauce.
Non-standard: Marinade the meat in wine for half an hour.
Standard: Macerate the fruit in wine for half an hour.
Non-standard: Marinate the fruit in wine for half an hour.
me, myself, and I. In a traditional prescriptive grammar, I is used only as a subject, me is used only as an object, and myself is used only as a reflexive object, that is to say when the subject is "I" and the object would otherwise be "me". Myself is often used incorrectly, often in a form of hypercorrection. Like the other reflexive pronouns, myself should be used only when both the subject and object of the verb are the speaker, or as an emphatic pronoun (intensifier).
Standard: Jim and I took the train.
Standard: He lent the books to Jim and me.
Standard: That is I in the picture. (This is very formal, and seldom found in speech.)
Acceptable: That is me in the picture. (This is typical in informal English.)
Standard (intensifying): I myself have seen instances of that type.
Standard (reflexive): I hurt myself. I did it to myself. I played by myself. I want to enjoy myself.
Non-standard: Jim and me went into town.
Non-standard: Me and Jim went into town.
Non-standard: As for myself, I prefer the red.
Non-standard: He is an American like myself.
Non-standard: He gave the paper to Jim and myself.
Non-standard: My wife and myself do not like the development.
Non-standard: 'I wake up/With my eyes shut tight/Hoping tomorrow will never come/For you and I.' (Should be For you and me) (From "You And I, Part II" by Fleetwood Mac)
mitigate and militate. To mitigate is to make something milder, typically something undesirable, and takes no preposition. To militate is to fight or exert pressure for something to happen or not to happen; it is typically followed by a preposition.
Standard: The seriousness of your crime was mitigated by the provocation you were under.
Standard: Over-protective practices in this factory militate against increased efficiency.
Non-standard: Over-protective practices in this factory mitigate against increased efficiency.
novice and novitiate. A novice is a prospective or trainee member, as of a religious order. The novitiate is the state of being a novice, or the time for which one is a novice. However, a novice monk or nun is often incorrectly described as "a novitiate" (perhaps confused with "initiate").
of and have. In some dialects of spoken English, of and the contracted form of have, 've, sound alike. However, in standard written English, they are not interchangeable.
Standard: Susan would have stopped to eat, but she was running late.
Standard: You could have warned me!
Non-standard: I should of known that the store would be closed. (Should be "I should've known")
overestimate and underestimate. There is frequent confusion between things that cannot and should not be over/underestimated, though the meanings are opposite.
Standard: The damage caused by pollution cannot be overestimated (i.e. it is so enormous that no estimate, however high, is excessive)
Standard: The damage caused by pollution should not be overestimated (i.e. while significant, it would be wrong to exaggerate it)
Standard: The damage caused by pollution should not be underestimated (i.e. it is wrong to regard it as minor)
Non-standard: The damage caused by pollution cannot be underestimated (literal meaning: it is so minimal that no estimate is too small. Intended meaning: as in the first or third example)
pallet, palate and palette. A pallet is a wooden platform or a thin sleeping mattress placed on the floor. The palate is the roof of the mouth, used to refer to one's tastes in food. An artist paints using a palette.
Standard: After unloading the boxes from the pallets, I slept on a pallet on the floor.
Standard: My palate is not very refined.
Standard: The artist placed globs of varying paint colors on his palette before beginning to paint.
Non-standard: This food always pleases my pallet.
Non-standard: When it comes to spiciness level, everyone's palette is different.
past and passed. Past refers to events that have previously occurred, while passed is the past tense of "to pass", whether in a congressional action or a physical occurrence.
Standard: Congress passed the bill limiting the powers of the President.
Standard: History is mainly concerned with the events of the past.
Non-standard: He past my house on his way to the store.
peremptory and preemptive. A peremptory act or statement is absolute; it cannot be denied. A preemptive action is one taken before an adversary can act.
Standard: He issued a peremptory order.
Standard: Preemptive air strikes stopped the enemy from launching the new warship.
perpetrate and perpetuate. To perpetrate something is to commit it, while to perpetuate something is to cause it to continue or to keep happening.
Standard: The gang perpetrated outrages against several citizens.
Standard: The stories only serve to perpetuate the legend that the house is haunted.
perquisite and prerequisite. Perquisite usually means 'an extra allowance or privilege'. Prerequisite means 'something required as a condition'.
Standard: He had all the perquisites of a movie star, including a stand-in.
Standard: Passing the examination was one of the prerequisites for a teaching position.
perspective and prospective. Perspective is a view with correct visual angles, example: parallel railway tracks converging in the distance. "Prospective" is a future possibility or expectation.
perspicuity and perspicacity. If something is perspicuous, it is easily understood; its meaning is obvious. If one is perspicacious, then one is quick to understand or has good insight.
Standard: I admired her perspicacity; she just seemed to get it so much better than I.
Standard: He expressed the idea so perspicuously that anyone could understand.
Non-standard: She spoke in a perspicacious way.
photogenic and photographic. The former is to be used to mean someone's likeness is particularly amenable to being well photographed. The latter is anything pertaining to photography whether it is technical e.g. photographic chemical or equipment, or generic e.g. photographic journals.
practice and practise. In British English, practice is the noun and practise is the verb, although this distinction is not maintained in American English.
prescribe and proscribe. To prescribe something is to command or recommend it. To proscribe somebody or something is to outlaw him, her or it.
prevaricate and procrastinate. To prevaricate is to avoid telling the truth. To procrastinate is put off doing something that needs to be done. 
redundant does not mean "useless" or "unable to perform its function". It means that there is an excess of something, that something is "surplus to requirements" and no longer needed.
Standard: The week before Christmas, the company made seventy-five workers redundant.
Standard: A new pill that will instantly cure any illness has made antibiotics redundant. (Antibiotics could still be used to cure illnesses, but they are no longer needed because a better pill has been invented.)
Non-standard: Over-use of antibiotics risks making them redundant. (This should read: over-use of antibiotics risks making them ineffective)
regimen and regiment. A regimen is a system of order, and may often refer to the systematic dosing of medication. A regiment is a military unit.
Standard: The sick soldier was removed from his regiment.
Standard: The sick soldier was ordered to complete a regimen of amoxicillin.
Non-standard: But wow, without the daily regiment of basketball, imagine what will happen to him?
Non-standard: Sports, science and technology are converging at an all-time pace and eight NBA teams are experimenting with a new device designed to optimize and personalize training regiments, thus the ability to maximize performance and reduce injury.
reign and rein. A reign refers to the rule of a monarch.Reins are the straps used to control the movements of an animal (typically a horse). Thus, to "take the reins" means to assume control, and to have "free rein" means to be free of constraints.
Non-standard: ...the Suns gave Sports Illustrated's Jack McCallum free reign of practices...
Non-standard: Bobby Jindal, a whiz kid takes the reigns of Louisiana's Department of Health and Hospital
Non-standard: Taylor will be passing on the reigns of the neighborhood school to Assistant Principal Amy Kleiner.
Non-standard: ...his rein of terror in 1969 is fascinating part of the history of 20th century crime...
Non-standard: He spent the last four seasons trying to patch together lineups in Houston, where injuries reined supreme, and he had a great deal of success under the circumstances.
Non-standard: Wesley Johnson: It's more that Johnson was proven a long-limbed bust before Lindsey Hunter and a tanking Phoenix team gave him free reign to jack triples and perhaps clarify his NBA destiny. Johnson still shot just 32 percent from deep amid all that freedom; his chances of membership here look slim.
Non-standard: Over 13 games, he averaged 15.5 points and 9.9 assists while shooting 44.8 percent from 3-point range (while reigning in his attempts a bit).
Non-standard: If you’re Mike Lupica you have the biggest column in one of America’s largest circulation newspapers, you host a prestige show on ESPN each week and you have, presumably, free reign to talk about whatever you want to talk about in sports.
reluctant and reticent. Reticent means quiet and unwilling to speak; reluctant means unwilling to do something.
Standard: He was reluctant to come to the party.
Standard: He is reticent in expressing his feelings.
Non-standard: He is reticent to press charges.
revert. To revert is to return to a former state, not to reply or respond to someone.
Standard: The Hulk reverted to Bruce Banner after he had a nice cup of tea and calmed down a bit.
Non-standard: Thanks for your email, I will look into this and revert to you.
sensual and sensuous. Both words mean "to do with the senses". Sensual is more often applied to a pleasure or experience or to a person's character; sensuous to someone or something of enticing appearance.
Standard: Don Juan is the most sensual character in fiction.
Standard: Ascetics believe in avoiding all sensual pleasures.
Standard: Marilyn Monroe looks extremely sensuous in this film clip.
set and sit. When used as a transitive verb, to set means "to place" or "to adjust to a value", whereas to sit means "to be seated".
Standard: Set the pot upon the stove.
Standard: Set the temperature-control to 100 °C.
Non-standard: Set down over there.
Standard: Sit on the chair.
shirk and shrink. To shirk means "to consistently avoid", "to neglect", "to be too afraid to engage". To shrink means "to contract", "to become physically smaller in size"; also, to shrink away means, "to suddenly jerk away from something in horror". However, to shrink from may also mean, "to hesitate or show reluctance toward".
Standard: I will not shirk discussion.
Standard: I will not shrink from discussion.
Standard: She shrank away from me.
Non-standard: I will not shrink discussion.
Non-standard: I will not shirk from discussion.
since and sense. Since is used as an adverb or a preposition to imply the same meaning as "after then" or "from" in a sentence. Sense is a noun meaning any method to gather data about an environment.
Standard: I have known her since last year.
Standard: My sense of smell is weak.
Non-standard: I won't go sense I have no fuel.
Non-standard: I can since your aura.
cite, sight and site. A sight is something seen; a site is a place. To cite is to quote or list as a source.
Standard: You are a sight for sore eyes.
Standard: I found a list of the sights of Rome on a tourist site.
Standard: Please cite the sources you used in your essay.
Standard: You must travel to the site of the dig to see the dinosaur bones.
Standard: It is necessary to have line-of-sight if you want to use semaphore.
Non-standard: One must be careful on a construction sight.
Non-standard: I will site the book in which I saw the statistics.
Non-standard: I could not fire because I did not have line-of-site to the target.
temblor and trembler. A temblor is an earthquake. A trembler is something that trembles.
their, there, they're, and there're. There refers to the location of something. Their means "belonging to them". They're is a contraction of "they are". There're is a contraction of "there are".
Standard: There're five of them, and they're all coming to the restaurant for their dinner; we will meet them there.
Non-standard: I don't like peanuts because of there texture when being chewed.
Non-standard: Bobby and Sally are coming over later and there bringing some friends with them.
Non-standard: The dogs are lying over their in the shade.
there's, where's, etc. A common spoken mistake is using a singular contraction when it should be plural in words like there's and where's. This stems from the fact that there're and where're are more difficult to enunciate and are often avoided for that reason in colloquial speech.
Non-standard: Where's the cars? (Should be Where're or where are)
Non-standard: There's many types of car. (Should be There are)
throe and throw. Throe is a spasm. Throw means to pass an object back and forth through the air.
to and too. Too means "in excess" or "also". To is a preposition or is a part of a verb in the infinitive. At the end of a sentence to may also refer to a dropped verb in the infinitive.
Standard: I have too much time on my hands.
Standard: Kick it to me.
trimester. A trimester is a period of three months. Because it is most commonly used in conjunction with a nine-month academic year or a nine-month term of human pregnancy, it is sometimes wrongly assumed that trimester is simply a synonym for one third.
Non-standard: Without further delay, then, comes ESPN.com's annual (and overdue) First Trimester Report, ushering folks back to the office by taking stock of the season's opening third:
venal and venial. These words are sometimes confused; venal means "corrupt", "able to be bribed", or "for sale"; venial means "pardonable, not serious".
Standard: According to Catholic doctrine, eating meat on a Friday during Lent is a venial sin, but murder is a mortal sin.
Standard: All ages have examples of venal politicians.
want, won't and wont. Want means the act of desiring or wishing for something. Won't is a contraction for "will not", while wont is a word meaning "accustomed" or "inclined to" (as an adjective) or "habit or custom" (as a noun).
Standard: He won't let me drive his car.
Standard: He spent the morning reading, as he was wont to do.
Standard: He took a walk in the evening, as was his wont.
Standard: His only want was to see his son again.
Non-standard: I wont need to go to the supermarket after all.
Non-standard: He took a walk in the evening, as was his want.
warrantee and warranty. A warranty is a legal assurance that some object can perform some specified task or meets certain quality standards. A warrantee is the person who benefits from a warranty. The verb form is warrant. Confusion here can stem from guarantee and the less common guaranty, which have similar meanings.
Standard: Most new cars come with at least a three-year warranty.
Standard: I guarantee that you will make a return on your investment.
Non-standard: Your mobile phone has stopped working? Maybe you need to claim under the warrantee.
who's and whose. Whose is an interrogative word (Whose is this?) or a relative pronoun (The people whose house you admired); who's is a contraction for "who is" or "who has".
Non-standard: "Which brings us right back to Del Negro, whose navigated this mercurial stretch seamlessly."
woman and women. Woman is the singular form of the word for an adult human female. Women is the plural form.
you're and your. While they sound the same in many dialects, in standard written English they have separate meanings. You're is a contraction of "you are", and your is a possessive pronoun meaning "belonging to you". When in doubt, check whether the word in question can logically be expanded to "you are".
Standard: When driving, always wear your seatbelt.
Standard: If you're going out, please be home by ten o'clock.
Non-standard: You also can't use 4G or LTE if you're Android phone doesn't support Bluetooth tethering.
Non-standard: You're mother called this morning.
Non-standard: Your the first person to notice my new haircut today!