Definition - A figure of speech where something is described by using words that are not literally applicable.

Example -

(1) Unmerciful people have hearts of steel.
(2) Ideas are food for thought.

Etymology -
The word ultimately derives from the Greek metaphora, a transfer (from meta, over or across + pherein, to carry or to bear).

Oxford English Dictionary -
Its first citation is from 1533:
"And rather then men would note a lye when they know what is meant, they will sooner by allegory or metaphor draw the word to the truth."
(Hen. VIII in Wotton Lett. (1654) Suppl. 8)

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