The Oxford Thesaurus An A-Z Dictionary of Synonyms - absurdadj.

1) ridiculous, silly, nonsensical, senseless, outlandish, preposterous, farcical, mad, stupid, foolish, idiotic, imbecilic or imbecile, moronic, childish; laughable, ludicrous, risible, inane, Colloq crazy, nutty, nuts , Chiefly Brit daft: The notion that the moon is made of green cheese is absurd. 2) asinine, senseless, illogical, irrational, unreasoned, unreasonable, incongruous, paradoxical, unsound, meaningless: Today, most people view it absurd to believe that the earth is flat.