senility vs years

senility and years both are nouns.

Word	Noun	Adjective	Verb	Adverb
senility	Yes	No	No	No
years	Yes	No	No	No

As nouns, years is a hypernym of senility; that is, years is a word with a broader meaning than senility:

senility: mental infirmity as a consequence of old age; sometimes shown by foolish infatuations
years: a late time of life

Other hypernyms of senility include age, eld, geezerhood, old age.

senility (noun)	years (noun)
the state of being senile	a late time of life
mental infirmity as a consequence of old age; sometimes shown by foolish infatuations	a prolonged period of time
	the time during which someone's life continues