"to turn (something) in an opposite direction; reverse the position, order, or sequence of," 1530s, from French invertir or directly from Latin invertere "turn upside down, turn about; upset, reverse, transpose," figuratively "pervert, corrupt, misrepresent," of words, "to use ironically," from in- "in, on" (from PIE root *en "in") + vertere "to turn" (from PIE root *wer- (2) "to turn, bend"). Related: Inverted; inverting; invertedly.

"turned in the opposite direction, having an opposite course or tendency," in early use also enverse, mid-15c., from Latin inversus, past participle of invertere "turn about, turn upside-down, upset, reverse, invert" (see invert). Related: Inversely. As a noun, "inverted state or condition," 1680s, from the adjective.

1540s, "contrary to nature, reason, or common sense," from Latin praeposterus "absurd, contrary to nature, inverted, perverted, in reverse order," literally "before-behind" (compare topsy-turvy,cart before the horse), from prae "before" (see pre-) + posterus "subsequent, coming after," from post "after" (see post-).

The sense gradually shaded into "foolish, ridiculous, stupid, absurd." The literal meaning "reversed in order or arrangement, having that last which ought to be first" (1550s) is now obsolete in English. In 17c. English also had a verb preposterate "to make preposterous, pervert, invert." Related: Preposterously; preposterousness.