inquiring vs challenge

inquiring and challenge both are nouns.

Word	Noun	Adjective	Verb	Adverb
inquiring	Yes	Yes	No	No
challenge	Yes	No	Yes	No

As nouns, challenge is a hyponym of inquiring; that is, challenge is a word with a more specific, narrower meaning than inquiring:

Other hyponyms of inquiring include enquiry, inquiry, interrogation, query, question, examination, interrogation, interrogatory.

inquiring (noun)	challenge (noun)
a request for information	a call to engage in a contest or fight
	questioning a statement and demanding an explanation
	a formal objection to the selection of a particular person as a juror
	a demand by a sentry for a password or identification
	a demanding or stimulating situation

inquiring (adjective)	challenge (adjective)
given to inquiry

inquiring (verb)	challenge (verb)
	issue a challenge to
	take exception to
	raise a formal objection in a court of law
	ask for identification