Preposterous

Part of speech: adjective (a.)

1. Having that first which ought to be last; inverted in order. [Obs.] The method I take may be censured as preposterous, because I thus treat last of the antediluvian earth, which was first in the order of nature. Woodward.

2. Contrary to nature or reason; not adapted to the end; utterly and glaringly foolish; unreasonably absurd; perverted. "Most preposterous conclusions." Shak. Preposterous ass, that never read so far! Shak.

Synonyms: Absurd; perverted; wrong; irrational; foolish; monstrous. See Absurd. Pre*pos"ter*ous*ly, adv. -Pre*pos"ter*ous*ness, n.