n.
Figure of speech in which a word or phrase denoting one kind of object or action is used in place of another to suggest a likeness or analogy between them (as in "the ship plows the seas" or "a volley of oaths").
A metaphor is an implied comparison (as in "a marble brow"), in contrast to the explicit comparison of the simile ("a brow white as marble"). Metaphor is common at all levels of language and is fundamental in poetry, in which its varied functions range from merely noting a likeness to serving as a central concept and controlling image.