asthenia vs infirmity

asthenia and infirmity both are nouns.

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

As nouns, infirmity is a hypernym of asthenia; that is, infirmity is a word with a broader meaning than asthenia:

asthenia: an abnormal loss of strength
infirmity: the state of being weak in health or body (especially from old age)

Other hypernyms of asthenia include debility, feebleness, frailness, frailty, valetudinarianism.

asthenia (noun)	infirmity (noun)
an abnormal loss of strength	the state of being weak in health or body (especially from old age)