35 synonyms for absurd such as crazy, astonishing, and barmy. Absurd is an adjective, and its antonyms are reasonable and sensible.
Astonishing, barmy, crazy, daft, fantastic, farcical, foolish, grotesque, hare-brained, idiotic, illogical, imbecilic, implausible, inane, incongruous, incredible, insane, irrational, laughable, ludicrous, monstrous, nonsensical, outrageous, pointless, preposterous, ridiculous, risible, senseless, shocking, silly, stupid, unbelievable, unreasonable, and unthinkable.