From WordNet (r) 3.0 (2006) [wn]:
loopy
adj 1: consisting of or covered with or having loops
2: informal or slang terms for mentally irregular; "it used to
drive my husband balmy" [syn: 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]