Nouns

(n)crazy, loony, looney, nutcase, weirdosomeone deranged and possibly dangerous

Adjectives

(s)brainsick, crazy, demented, disturbed, mad, sick, unbalanced, unhingedaffected with madness or insanity“a man who had gone mad”
(s)crazy, half-baked, screwball, softheadedfoolish; totally unsound“a crazy scheme”, “half-baked ideas”, “a screwball proposal without a prayer of working”
(s)crazypossessed by inordinate excitement“the crowd went crazy”, “was crazy to try his new bicycle”
(s)crazybizarre or fantastic“had a crazy dream”, “wore a crazy hat”
(s)crazy, wild, dotty, gagaintensely enthusiastic about or preoccupied with“crazy about cars and racing”, “they are dotty about each other”, “gaga over the rock group's new album”