Preposterous
mid 16th century: from Latin praeposterus ‘reversed, absurd’ (from prae ‘before’ + posterus ‘coming after’) + -ous.
wiktionary
From Latin praeposterus(“with the hinder part before, reversed, inverted, perverted”), from prae(“before”) + posterus(“coming after”).
etymonline
preposterous (adj.)
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.
