debility vs infirmity

debility and infirmity both are nouns.

Word	Noun	Adjective	Verb	Adverb
debility	Yes	No	No	No
infirmity	Yes	No	No	No

As nouns, debility and infirmity are synonyms defined as:

debility and infirmity: the state of being weak in health or body (especially from old age)

Other synonyms of debility include feebleness, frailness, frailty, valetudinarianism.

debility (noun)	infirmity (noun)
the state of being weak in health or body (especially from old age)	the state of being weak in health or body (especially from old age)