asthenia vs feebleness

asthenia and feebleness both are nouns.

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

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

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

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

asthenia (noun)	feebleness (noun)
an abnormal loss of strength	the quality of lacking intensity or substance
	the state of being weak in health or body (especially from old age)