athletics vs underhand

athletics is a noun but underhand is not a noun.

Word	Noun	Adjective	Verb	Adverb
athletics	Yes	No	No	No
underhand	No	Yes	No	Yes

athletics (noun)	underhand (noun)
an active diversion requiring physical exertion and competition
participation in sports events as an extracurricular activity
a contest between athletes

athletics (adjective)	underhand (adjective)
	with hand brought forward and up from below shoulder level
	marked by deception

athletics (adverb)	underhand (adverb)
	with the hand swung below shoulder level
	slyly and secretly