balmy, barmy(chiefly British), bats, batty, bedlam, bonkers, brainsick, bughouse(slang), certifiable, crackbrained, cracked, crackers, crackpot, cranky(dialect), crazed, crazy, cuckoo, daffy, daft, demented, deranged, fruity(slang), gaga, haywire, insane, kooky(also kookie), loco(slang), loony(also looney), loony tunes(or looney tunes), lunatic, mad, maniacal(also maniac), mental, meshuga(or meshugge also meshugah or meshuggah), moonstruck, non compos mentis, nuts, nutty, psycho, psychotic, scatty(chiefly British), screwy, unbalanced, unhinged, unsound, wacko(also whacko), wacky(also whacky), wud(chiefly Scottish)

dotty, fey, loopy, off, potty(chiefly British), teched(or tetched), touchedaberrant, delirious, delusional, delusionary, disordered, disturbed, neurotic, obsessive-compulsive, paranoiac(also paranoic), paranoid(also paranoidal), schizoid, schizophrenic, sociopathiceccentric, odd, oddball, pixilated(also pixillated), queer, strangefoolish, senseless, witlessirrational, unreasonableamok(or amuck), ape, ballistic, bananas, berserk, nucleardepresseddistracted, distraught, frantic, frenzied, haywire, hysterical(also hysteric), raving, wigged-outfixated, monomaniac, monomaniacal, obsessed

around the bend, off one's gourd, off one's head, off one's rocker, out to lunch(slang)