screwball

nouns

a whimsically eccentric person
crackpot, crank, fruitcake, nut, nut case, screwball
a pitch with reverse spin that curves toward the side of the plate from which it was thrown
screwball
is a type of (narrower)
(baseball) the act of throwing a baseball by a pitcher to a batter
delivery, pitch

adjectives

foolish; totally unsound
"a crazy scheme"; "half-baked ideas"; "a screwball proposal without a prayer of working"
crazy, half-baked, screwball, softheaded