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.
In Catholic teaching an omission is a failure to do something one can and ought to do. If this happens advertently and freely, it is considered a sin.
The degree of guilt incurred by an omission is measured like that attaching to sins of commission, by the dignity of the virtue and the magnitude of the precept to which the omission is opposed as well as the amount of deliberation.