frailness vs feebleness

frailness and feebleness both are nouns.

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

As nouns, frailness and feebleness are synonyms defined as:

frailness and feebleness: the state of being weak in health or body (especially from old age)

Other synonyms of frailness include debility, frailty, infirmity, valetudinarianism.

frailness (noun)	feebleness (noun)
the state of being weak in health or body (especially from old age)	the quality of lacking intensity or substance
	the state of being weak in health or body (especially from old age)