WordNet sense 1 (informal or slang terms for mentally irregular):

balmy, batty, bonkers, buggy, cracked, crackers, daft, fruity, haywire, kooky, loco, loony, loopy, nuts, nutty, wacky, barmy, kookie, whacky, around the bend, bats, round the bend

WordNet sense 2 (afflicted with or characteristic of mental derangement):

insane

WordNet sense 3 (marked by foolish or unreasoning fondness):

crazy, enamored, gaga, infatuated, smitten, in love

WordNet sense 4 (feeling or showing love and affection):

loving