from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Baseball A pitched ball that curves in the direction opposite to that of a normal curve ball.
- n. Slang An eccentric, impulsively whimsical, or irrational person.
- adj. Slang Impulsively whimsical; eccentric: That screwball proposal won't work.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A pitch thrown with added pressure by the index finger and a twisting wrist motion resulting in a motion to the right when thrown by a right-handed pitcher.
- n. One who behaves in a crazy manner.
- adj. Crazy, offbeat, bizarre, zany, or weird.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a whimsically eccentric person
- adj. foolish; totally unsound
- n. a pitch with reverse spin that curves toward the side of the plate from which it was thrown
From screw + ball (Wiktionary)