Figure of Speech
Conceit
From Italian concetto: concept. The Petrarchan conceit (lover as ship, heart as battlefield) was parodied by Shakespeare; the metaphysical conceit (Donne, Herbert) pushed comparison to its limits.
Definition
An elaborate, extended metaphor that draws a surprising or ingenious comparison between apparently unlike things.
Example
Donne's 'A Valediction: Forbidding Mourning': separated lovers' souls compared to the two legs of a draughtsman's compass.