Metaphor

Metaphor is a figure of speech that refers, for rhetorical effect, to one thing by mentioning another thing. It may provide clarity or identify hidden similarities between two ideas. Antithesis, hyperbole, metonymy and simile are all types of metaphor. One of the most commonly cited examples of a metaphor in English literature is the "All the world's a stage" monologue from As You Like It:

All the world's a stage,

And all the men and women merely players;

They have their exits and their entrances[...]

—William Shakespeare, As You Like It, 2/7

This quotation expresses a metaphor because the world is not literally a stage. By asserting that the world is a stage, Shakespeare uses points of comparison between the world and a stage to convey an understanding about the mechanics of the world and the behavior of the people within it.

The Philosophy of Rhetoric (1937) by rhetorician I. A. Richards describes a metaphor as having two parts: the tenor and the vehicle. The tenor is the subject to which attributes are ascribed. The vehicle is the object whose attributes are borrowed. In the previous example, "the world" is compared to a stage, describing it with the attributes of "the stage"; "the world" is the tenor, and "a stage" is the vehicle; "men and women" is the secondary tenor, and "players" is the secondary vehicle.

Other writers employ the general terms ground and figure to denote the tenor and the vehicle. Cognitive linguistics uses the terms target and source, respectively.