frailty vs asthenia

frailty and asthenia both are nouns.

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

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

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

Other hyponyms of frailty include astheny, cachexia, cachexy, wasting, sickliness.

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