- balmy, barmy, bats, batty, bonkers, buggy, cracked, crackers, daft, dotty, fruity, haywire, kooky, kookie, loco, loony, loopy, nuts, nutty, round the bend, around the bend, wacky, whacky - informal or slang terms for mentally irregular; "it used to drive my husband balmy"
Antonym: sane (indirect, via insane)