WordNet sense 1 (a small lightweight carriage; drawn by a single horse):

roadster

WordNet sense 2 (informal or slang terms for mentally irregular):

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

WordNet sense 3 (afflicted with or characteristic of mental derangement):

insane

WordNet sense 4 (soiled or likely to soil with dirt or grime):

dirty, unclean, soiled