screwball vs half-baked

screwball is a noun but half-baked is not a noun.

Word	Noun	Adjective	Verb	Adverb
screwball	Yes	Yes	No	No
half-baked	No	Yes	No	No

As adjectives, screwball and half-baked are synonyms defined as:

Other synonyms of screwball include crazy, softheaded.

screwball (noun)	half-baked (noun)
a pitch with reverse spin that curves toward the side of the plate from which it was thrown
a whimsically eccentric person

screwball (adjective)	half-baked (adjective)
foolish; totally unsound	foolish; totally unsound
	insufficiently cooked