infirmity vs cachexy

infirmity and cachexy both are nouns.

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

As nouns, cachexy is a hyponym of infirmity; that is, cachexy 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)
cachexy: any general reduction in vitality and strength of body and mind resulting from a debilitating chronic disease

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

infirmity (noun)	cachexy (noun)
the state of being weak in health or body (especially from old age)	any general reduction in vitality and strength of body and mind resulting from a debilitating chronic disease