- Slang. an eccentric or whimsically eccentric person; a nut.
- Baseball. a pitched ball that curves toward the side of the plate from which it was thrown.
- Slang. eccentric or whimsically eccentric: What a screwball idea!
- an odd or eccentric person
- odd; zany; eccentric
n.“eccentric person,” 1933, U.S. slang, earlier as a type of erratic baseball pitch (1928), from a still earlier name for a type of delivery in cricket (1866), from screw (n.) + ball (n.1). Screwball comedy is attested from 1938, in reference to Carole Lombard.