also ditsy, "stupid, scatterbrained" (especially of women), by 1973, U.S. slang, of unknown origin; one guess is that it is related to earlier U.S. black slang dicty (1926) "conceited, snobbish," also of unknown origin, but the sense is very difficult. The noun ditz (1982) appears to be a back-formation.
Vapid and frivolous; silly; airheaded: Charles Ruggles's ditsy bimbo/ Is there something in the air that makes Washington wives ditsy?
[mid-1970s+; perhaps a blending of dizzy and dotty]