metaphor [Gr., = transfer], in rhetoric, a figure of speech in which one class of things is referred to as if it belonged to another class. Whereas a simile states that A is like B, a metaphor states that A is B or substitutes B for A. Some metaphors are explicit, like Shakespeare's line from As You Like It : "All the world's a stage." A metaphor can also be implicit, as in Shakespeare's Sonnet LXXIII, where old age is indicated by a description of autumn:
A dead metaphor, such as "the arm" of a chair, is one that has become so common that it is no longer considered a metaphor.
That time of year thou mayst in me behold
Where yellow leaves, or none, or few, do hang
Upon those boughs which shake against the cold,
Bare ruined choirs, where once the sweet birds sang.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.