Entry 1 sense Webster, 1913 crackers · IPA /krˈækərz/ 01 adj. crazy. 1. crazy.[informal or slang] Syn. balmy, barmy, bats, batty, bonkers, buggy, cracked, daft, dotty, fruity, haywire, kooky, kookie, loco, loony, loopy, nuts, nutty, wacky.