Wiktionary:Literal and figurative language

Literal language
There is no real consensus on the meaning of literal language. In the traditional analyses, words in literal expressions denote what they mean according to common or dictionary usage, while words in figurative expressions connote additional layers of meaning.

In Wiktionary everything that is not marked as otherwise is considered to be literal language.

Figurative language
Figurative language uses figures of speech that is words or phrases that departs from straightforward, literal language. Figures of speech are often used and crafted for emphasis, freshness of expression, or clarity. However, clarity may also suffer from their use.

There are several different figures of speech, but many do not carry much additional meaning beyond the literal one. They are mostly used to convince, educate or entertain, so they don't really need any additional marking if they are be included in Wiktionary at all.

The following ones do carry additional meaning to a greater or lesser degree and thus needs to marked. Note that they are not strictly mutually exclusive. For example, all similes are metaphors, all synecdoches are metonyms which in turn are metaphors. However, there is no real consensus on when to use the more specialized terms.

Idioms
An idiom is phrase that cannot be fully understood from the separate meanings of the individual words which form it.

Metaphors and similes
A metaphor is a word or a phrase to refer to something that it isn't, implying a similarity between the word or phrase used and the thing described, if the metaphor does an explicit comparison with the words "like" and "as" it is called a simile.

Metonyms and synecdoches
A metonym is a word or phrase that replaces another and uses of a single characteristic to identify a more complex entity. If a specific part of something is taken to refer to the whole, it is called a synecdoche.

Euphemisms
A euphemism is a word or phrase that replaces another and that is considered less offensive or less vulgar than the word or phrase it replaces.

Dysphemisms and cacophemisms
A dysphemism is a word or phrase that replaces another and that is considered more offensive or more vulgar than the word or phrase it replaces. If it deliberately offensive instead of merely humorously deprecating, it is called a cacophemism.

Hyperboles
An hyperbole is a word or phrase that replaces another and that is usually extremely exaggerated or extravagant. While what is a hyperbole or not is to large extent context dependent and not usually an inherent property of some meaning of the word or phrase itself, some words or phrases have meanings that should be marked.

Understatements
An understatement is a word or phrase that replaces another where a lesser expression is used than what would be expected. However, since what is an understatement or not is to a large extent context dependent and not usually an inherent property of some meaning of the word or phrase itself, no special marking should be used in most cases.