metaphor

n. A form of speech in which a word or phrase is applied to another word or idea that it does not actually denote in order to convey a meaning difficult to convey otherwise. Thus one can say, "Life is a cabaret," which is not literally true but conveys meaning about a point of view on the nature of life, or "The brain is a computer," which is also not true but points out aspects of brain function one might not otherwise notice.