Emily Dickinson Lexicon

TROPE, n. [L. tropus; Gr. τροπος, from τρεπω, to turn; W. trova, a turn, a tropic; trovâu, to turn.]

In rhetoric, a word or expression used in a different sense from that which it properly signifies; or a word changed from its original signification to another, for the sake of giving life or emphasis to an idea, as when we call a stupid fellow an ass, or a shrewd man a fox. Tropes are chiefly of four kinds, metaphor, metonymy, synecdoche, and irony. Some authors make figures the genus, of which trope is a species; others make them different things, defining trope to be a change of sense, and figure to be any ornament, except what becomes so by such change.