Not truly or strictly belonging to the thing under consideration; not in accordance with truth, fact, reason, or rule; abnormal, irregular…

Contrary to nature, reason, or common sense; monstrous; foolish, perverse. Now chiefly: utterly absurd or ridiculous; outrageous.

Of a phenomenon, circumstance, etc.: exhibiting some contradiction with itself or with known laws, esp. laws of nature; hard to reconcile with known…

spec. As a philosophical term.

gen. Paradoxical.