Synonyms for Crazy:

adj.

absurd (adjective)
absurd, anachronistic, contradictory, fallacious, farcical, foolish, idiotic, illogical, implausible, impossible, inane, invalid, irrational, laughable, loony, ludicrous, meaningless, nonsensical, paradoxical, preposterous, ridiculous, self-contradictory, senseless, silly, bizarre, eccentric, incongruous, inconsistent, outlandish.
crazed (adjective)
berserk.
deranged (adjective)
nutty.
foolish (adjective)
asinine, blithering, blockheaded, brainless, cockeyed, cretinous, dim-witted, doltish, dopey, dotty, dumb, goofy, half-witted, ignorant, imbecilic, loony, moronic, nitwit, zany, crackpot, bone-headed, chuckle-headed, knuckle-headed, lame-brained, meat-headed, absurd, foolish, idiotic, inane, nonsensical, tomfool, dippy.
infatuated, in love (adjective)
ardent, enamored, hysterical, keen, smitten, zealous.
insane (adjective)
babbling, batty, berserk, delirious, demented, feverish, frenzied, hysterical, insane, kooky, lunatic, mad, maniacal, neurotic, nutty, psycho, psychotic, schizoid, unbalanced, Crack-brained, brain-sick, blithering, brainsick, deranged, gaga, irrational, moonstruck, bananas.
lunatic (adjective)
Fiendish, kooky, lunatic, mad, neurotic, nutty, psychotic, crackpot.
mentally strange (adjective)
batty, berserk, cuckoo, delirious, demented, deranged, erratic, idiotic, insane, kooky, lunatic, mad, maniacal, moonstruck, nutty, psycho, screwball, screwy, silly, touched, unbalanced, unhinged, dippy.
nonconforming (adjective)
aberrant, abnormal, anomalous, atypical, bizarre, crosspatch, curious, deranged, deviant, different, divergent, eccentric, erratic, exceptional, extraordinary, fey, freakish, funny, idiosyncratic, improper, incompatible, incongruous, inconsistent, irregular, misfit, mismatch, nonconforming, novel, odd, oddball, oddity, off, outlandish, peculiar, quirky, singular, strange, uncommon, unconventional, unfamiliar, unique, untypical, out of the ordinary, uncustomary, un-ordinary, unusual.
ridiculous (adjective)
comical, dubious, grotesque, incredible, laughable, outrageous, poppycock, weird, absurd, bizarre, curious, eccentric, farcical, foolish, ludicrous, nonsensical, oddball, outlandish, preposterous, ridiculous, silly.
screwy (adjective)
screwy.
unrealistic, fantastic (adjective)
absurd, bizarre, cockeyed, eccentric, foolish, goofy, half-baked, inane, loony, ludicrous, nonsensical, odd, outrageous, peculiar, preposterous, ridiculous, senseless, strange, weird.

n.

childish, over-the-top, not in your right mind/not right in the head. cuckoo, disordered, distraught, madwoman, mentally ill, moonstruck, non compos mentis, sane, screwy, space cadet, touched, unsound, wrong, Daffy, bananas, headcase, nutjob. ardent, concern, fervent, gung ho, keen, rabid, warm, zealous. ability, cockeyed, jerky, knowledge, sappy, tomfool, unearthly, zany, dippy. loon, wise, dingbat, ding-a-ling. crazy (noun)
brainsick, demented, distracted, disturbed, dotty, enamored, enthusiastic, excited, gaga, half-baked, impractical, in love, infatuated, insane, looney, loony, loving, mad, meshuga, meshugge, screwball, sick, smitten, soft on, softheaded, strange, taken with, unbalanced, unhinged, unusual, weirdo.
eccentric person (noun)
kook.
lunatic (noun)
crank, fiend, kook, madman, maniac, nut, psychopath.
person (noun)
looney, loony, weirdo.

Other synonyms:

cuckoo, gung ho, jerky, loon, mentally ill, non compos mentis, over-the-top, dingbat, Daffy, bananas, dippy, ding-a-ling. distraught, warm, zealous. ardent, childish, disordered, fervent, moonstruck, rabid, sappy, touched, unsound, zany. keen, unearthly. wrong. odd
screwy.
Other relevant words:
ability, ardent, brainsick, childish, cockeyed, concern, cuckoo, disordered, distracted, distraught, disturbed, enamored, enthusiastic, excited, fervent, gaga, half-baked, impractical, in love, infatuated, jerky, keen, knowledge, loon, looney, loving, madwoman, mentally ill, meshuga, meshugge, moonstruck, non compos mentis, over-the-top, rabid, sappy, screwball, screwy, sick, smitten, soft on, softheaded, taken with, tomfool, touched, unearthly, unhinged, unsound, warm, weirdo, wise, wrong, zany, zealous, dingbat, Daffy, bananas, dippy, ding-a-ling, headcase, nutjob.

Usage examples for crazy

  1. Sometimes he isn't so crazy – The Wrong Twin by Harry Leon Wilson
  2. Are you gone crazy – Footsteps of Fate by Louis Couperus
  3. We both must be going crazy to go on as we do. – Undertow by Kathleen Norris