infirmity vs astheny

infirmity and astheny both are nouns.

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

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

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

Other hyponyms of infirmity include asthenia, cachexia, cachexy, wasting, sickliness.

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