tightrope walking vs athletics

tightrope walking and athletics both are nouns.

Word	Noun	Adjective	Verb	Adverb
tightrope walking	Yes	No	No	No
athletics	Yes	No	No	No

As nouns, athletics is a hypernym of tightrope walking; that is, athletics is a word with a broader meaning than tightrope walking:

Other hypernyms of tightrope walking include sport.

tightrope walking (noun)	athletics (noun)
walking on a tightrope or slack rope	an active diversion requiring physical exertion and competition
	participation in sports events as an extracurricular activity
	a contest between athletes