senescence vs ageing

senescence and ageing both are nouns.

Word	Noun	Adjective	Verb	Adverb
senescence	Yes	No	No	No
ageing	Yes	Yes	No	No

As nouns, senescence and ageing are synonyms defined as:

senescence and ageing: the organic process of growing older and showing the effects of increasing age

Other synonyms of senescence include aging.

senescence (noun)	ageing (noun)
the property characteristic of old age	the organic process of growing older and showing the effects of increasing age
the organic process of growing older and showing the effects of increasing age	acquiring desirable qualities by being left undisturbed for some time

senescence (adjective)	ageing (adjective)
	growing old