A figure of speech is the use of a word or a phrase, which transcends its literal interpretation. It can be a special repetition, arrangement or omission of words with literal meaning, or a phrase with a specialized meaning not based on the literal meaning of the words in it, as in idiom, metaphor, simile, hyperbole, personification, or synecdoche. Figures of speech often provide emphasis, freshness of expression, or clarity. However, clarity may also suffer from their use, as any figure of speech introduces an ambiguity between literal and figurative interpretation. A figure of speech is sometimes called a rhetorical figure or a locution.
Rhetoric originated as the study of the ways in which a source text can be transformed to suit the goals of the person reusing the material. For this goal, classical rhetoric detected four fundamental operations that can be used to transform a sentence or a larger portion of a text: expansion, abridgement, switching, transferring and so on.
addition (adiectio), also called repetition/expansion/superabundance
omission (detractio), also called subtraction/abridgement/lack
transposition (transmutatio), also called transferring
permutation (immutatio), also called switching/interchange/substitution/transmutation
These four operations were detected by classical rhetoricians, and still serve to encompass the various figures of speech. Originally these were called, in Latin, the four operations of quadripartita ratio. The ancient surviving text mentioning them, although not recognizing them as the four fundamental principles, is the Rhetorica ad Herennium, of unknown authorship, where they are called πλεονασμός (addition), ἔνδεια (omission), μετάθεσις (transposition) and ἐναλλαγή (permutation). Quintillian then mentioned them in Institutio Oratoria.Philo of Alexandria also listed them as addition (πρόσθεσις), subtraction (ἀφαίρεσις), transposition (μετάθεσις), and transmutation (ἀλλοίωσις).
Figures of speech come in many varieties. The aim is to use the language inventively to accentuate the effect of what is being said. A few examples follow:
"Around the rugged rocks the ragged rascal ran" is an example of alliteration, where the consonant r is used repeatedly.
Whereas, "Sister Suzy sewing socks for soldiers" is a particular form of alliteration called sibilance, because it repeats the letter s.
Both are commonly used in poetry.
"She would run up the stairs and then a new set of curtains" is a variety of zeugma called a syllepsis. Run up refers to ascending and also to manufacturing. The effect is enhanced by the momentary suggestion, through a pun, that she might be climbing up the curtains. The ellipsis or omission of the second use of the verb makes the reader think harder about what is being said.
"Military Intelligence is an oxymoron" is the use of direct sarcasm to suggest that the military would have no intelligence. This might be considered to be a satire and an aphorism.
"But he's a soldier, so he has to be an Einstein" is the use of sarcasm through irony for the same effect. The use of hyperbole by using the word Einstein calls attention to the ironic intent.
"An Einstein" is an example of synecdoche, as it uses a particular name to represent a class of people: geniuses.
"I had butterflies in my stomach" is a metaphor, referring to my nervousness feeling as if there were flying insects in my stomach.
To say "it was like having some butterflies in my stomach" would be a simile, because it uses the word like which is missing in the metaphor.
Scholars of classical Western rhetoric have divided figures of speech into two main categories: schemes and tropes. Schemes (from the Greek schēma, form or shape) are figures of speech that change the ordinary or expected pattern of words. For example, the phrase, "John, my best friend" uses the scheme known as apposition. Tropes (from the Greek trepein, to turn) change the general meaning of words. An example of a trope is irony, which is the use of words to convey the opposite of their usual meaning ("For Brutus is an honorable man; / So aire they all, all honorable men").
During the Renaissance, scholars meticulously enumerated and classified figures of speech. Henry Peacham, for example, in his The Garden of Eloquence (1577), enumerated 184 different figures of speech. Professor Robert DiYanni, in his book "Literature - Reading Fiction, Poetry, Drama and the Essay"  wrote: "Rhetoricians have catalogued more than 250 different figures of speech, expressions or ways of using words in a nonliteral sense.".
For simplicity, this article divides the figures between schemes and tropes, but does not further sub-classify them (e.g., "Figures of Disorder"). Within each category, words are listed alphabetically. Most entries link to a page that provides greater detail and relevant examples, but a short definition is placed here for convenience. Some of those listed may be considered rhetorical devices, which are similar in many ways.
rhetorical question: Asking a question as a way of asserting something. Asking a question which already has the answer hidden in it. Or asking a question not for the sake of getting an answer but for asserting something (or as in a poem for creating a poetic effect)
superlative: Saying that something is the best of something or has the most of some quality, e.g. the ugliest, the most precious etc.
syllepsis: The use of a word in its figurative and literal sense at the same time or where a single word is used in relation to two other parts of a sentence although the word grammatically or logically applies to only one
syncatabasis (condescension, accommodation): adaptation of style to the level of the audience
synchoresis: A concession made for the purpose of retorting with greater force.
Using these formulas, a pupil could render the same subject or theme in a myriad of ways. For the mature author, this principle offered a set of tools to rework source texts into a new creation. In short, the quadripartita ratio offered the student or author a ready-made framework, whether for changing words or the transformation of entire texts. Since it concerned relatively mechanical procedures of adaptation that for the most part could be learned, the techniques concerned could be taught at school at a relatively early age, for example inthe improvement of pupils’ own writing.