A figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable. e.g., "Her eyes were glistening jewels."
A metaphor is a literary figure of speech that uses an image, story or tangible object to represent a less tangible object or some intangible quality or idea;
e.g., "Her eyes were glistening jewels."
Metaphor may also be used for any rhetorical figures of speech that achieve their effects via association, comparison or resemblance. In this broader sense, antithesis, hyperbole, and simile would all be considered types of metaphor.