athletics vs defending

athletics is a noun but defending is not a noun.

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

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

athletics (adjective)	defending (adjective)
	attempting to or designed to prevent an opponent from winning or scoring