The word(s) of the year, sometimes capitalized as "Word(s) of the Year" and abbreviated "WOTY" (or "WotY"), refers to any of various assessments as to the most important word(s) or expression(s) in the public sphere during a specific year. The oldest of these, and the only one that is announced after the end of the calendar year, determined by a vote of independent linguists, and not tied to commercial interests, is the American Dialect Society's Word of the Year. However, various other organizations also announce Words of the Year for promotional purposes.
2006:plutoed (demoted or devalued, as happened to the former planet Pluto)
2007:subprime (an adjective used to describe a risky or less than ideal loan, mortgage, or investment)
2008:bailout (in the specific sense of the rescue by the government of companies on the brink of failure, including large players in the banking industry)
2009:tweet (a short, timely message sent via the Twitter.com service, and verb, the act of sending such a message)
2010:app (an abbreviated form of application, a software program for a computer or phone operating system)
2011:occupy (verb or noun inspired from the Occupy movements of 2011)
2012:hashtag (a word or phrase preceded by a hash symbol (#), used on Twitter to mark a topic or make a commentary)
2013:because introducing a noun, adjective, or other part of speech (e.g., “because reasons,” “because awesome”).
2014:#blacklivesmatter: hashtag used as protest over blacks killed at the hands of police (esp. Michael Brown in Ferguson, Mo. and Eric Garner in Staten Island). 
The society also chose a "Word of the 1990s" (web), "Word of the 20th Century" (jazz), "Word of the Past Millennium" (she), and "Word of the Decade (2000–2009)" (google as a verb).
Other candidates for "Word of the Year" have included:
2014:bae: a sweetheart or romantic partner, columbusing: cultural appropriation, especially the act of a white person claiming to discover things already known to minority cultures, even: deal with or reconcile difficult situations or emotions (from “I can’t even”), manspreading: of a man, to sit with one’s legs wide on public transit in a way that blocks other seats.
2013:slash: used as a coordinating conjunction to mean “and/or” (e.g., “come and visit slash stay”) or “so” (“I love that place, slash can we go there?”), twerk: A mode of dance that involves vigorous booty-shaking and booty-thrusting, usually with the feet planted, Obamacare: term for the Affordable Care Act that has moved from pejorative to matter-of-fact shorthand and selfie: a photo taken of oneself, typically with a smartphone and shared on social media.
2012: Other nominees were YOLO (an acronym for “You Only Live Once,” often used sarcastically or self-deprecatingly), fiscal cliff (the threat of spending cuts and tax increases looming over end-of-year budget negotiations), Gangnam style (the trendy style of Seoul’s Gangnam district, as used in the Korean pop song of the same name), marriage equality (legal recognition of same-sex marriage), and 47 percent (a claimed portion of the population that does not pay federal income tax).
2007: Among the contenders were green- (a designation of environmental concern, as in greenwashing), surge (an increase in troops in a war zone, as in the Iraq War troop surge of 2007), Facebook (all parts of speech), waterboarding (an interrogation technique in which the subject is immobilized and doused with water to simulate drowning), Googlegänger (a portmanteau of Google and Doppelgänger, meaning a person with your name who shows up when you google yourself), and wide stance, "to have a —" (to be hypocritical or to express two conflicting points of view, in reference to Senator Larry Craig after his 2007 arrest at an airport)
2006:Plutoed beat "climate canary" (something whose poor health indicates a looming environmental catastrophe) in a run-off vote for the 2006 word of the year. Other words in the running were flog (an advertisement disguised as a blog or web log), The Decider (a political catchphrase said by former United States President George W. Bush), "prohibited liquids" (fluids that cannot be transported by passengers on airplanes), and macaca (an American citizen treated as an alien)
In addition to the "Word of the Year", the society also selects words in other categories that vary from year to year:
2014:even deal with or reconcile difficult situations or emotions (from “I can’t even”).
2013:because introducing a noun, adjective, or other part of speech (e.g., "because reasons," "because awesome").
2012:-(po)calypse, -(ma)geddon (hyperbolic combining forms for various catastrophes)
2011:humblebrag (expression of false humility, especially by celebrities on Twitter)
2010:prehab (preemptive enrollment in a rehab facility to prevent relapse of an abuse problem)
2009:Dracula sneeze (covering one’s mouth with the crook of one’s elbow when sneezing, seen as similar to popular portrayals of the vampire Dracula, in which he hides the lower half of his face with a cape)
2008:recombobulation area (an area at General Mitchell International Airport in which passengers that have passed through security screening can get their clothes and belongings back in order)
2014:baeless: without a romantic partner (lacking a bae).
2013:sharknado (a tornado full of sharks, as featured in the Syfy Channel movie of that name)
Occupy Words (2011):the 99%, 99 percenters (those held to be at a financial or political disadvantage to the top moneymakers, the one-percenters)
Fan Words (2010):gleek (a fan of the TV show Glee)
Election-Related Word (2008):maverick (a person who is beholden to no one, widely used by the Republican presidential and vice-presidential candidates John McCain and Sarah Palin)
The Macquarie Dictionary, which is the dictionary of Australian English, updates the online dictionary each year with new words, phrases and definitions. Each year the editors select a short list of new words added to the dictionary and invite the public to vote on their favourite. The public vote is held in January and results in the People’s Choice winner. The most influential word of the year is also selected by the Word of the Year Committee which is chaired by the Vice-Chancellor of the University of Sydney, Dr Michael Spence. The Editor of the Macquarie Dictionary, Susan Butler, is also a committee member. The Committee meets in early February to select the overall winning words.
The following is the list of winning words since the Macquarie Word of the Year first began in 2006:
The lists of Merriam-Webster's Words of the Year (for each year) are ten-word lists published annually by the American dictionary-publishing company Merriam-Webster, Inc., which feature the ten words of the year from the English language. These word lists started in 2003 and have been published at the end of each year. At first, Merriam-Webster determined its contents by analyzing page hits and popular searches on its website. Since 2006, the list has been determined by an online poll and by suggestions from visitors to the website.
The following is the list of words that became Merriam-Webster's Word of the Year since 2003:
Oxford University Press, which publishes the Oxford English Dictionary and many other dictionaries, announces an Oxford Dictionaries UK Word of the Year and an Oxford Dictionaries US Word of the Year; sometimes these are the same word. The Word of the Year need not have been coined within the past twelve months but it does need to have become prominent or notable during that time. There is no guarantee that the Word of the Year will be included in any Oxford dictionary. The Oxford Dictionaries Words of the Year are selected by editorial staff from each of the Oxford dictionaries. The selection team is made up of lexicographers and consultants to the dictionary team, and editorial, marketing, and publicity staff.
The Global Language Monitor (GLM) has been selecting the Top Words of the Year since 2000. GLM states the Top Words, Phrases, and Names of the Year provide a history of each year since 2000 through English-language word usage. To select these words and phrases, it uses a claimed statistical analysis of language usage in the worldwide print and electronic media, the Internet, and the blogosphere, as well as social media, though several linguists and lexicographers have charged that its mathematical methodologies are flawed. GLM announced their 2013 Top Words, Phrases and Names on November 5, 2013, thus launching the WOTY season, which will conclude with the ADA’s announcement in early January 2014.
Since 2004, Susie Dent, an English lexicographer has published a column, "A Word a Year", in which she chooses a single word from each of the last 101 years to represent preoccupations of the time. Susie Dent notes that the list is subjective. Each year, she gives a completely different set of words.
Since Susie Dent works for the Oxford University Press, her words of choice are often incorrectly referred to as "Oxford Dictionary’s Word of the Year".
In Germany, a Wort des Jahres has been selected since 1972 by the Society of the German Language. In addition, an Unwort des Jahres (Unword of the Year or No-no Word of the Year) has been nominated since 1991, for a word or phrase in public speech deemed insulting or socially inappropriate (such as "Überfremdung"). Similar selections are made each year since 1999 in Austria, 2002 in Liechtenstein and 2003 in Switzerland.