second childhood vs geezerhood

second childhood and geezerhood both are nouns.

Word	Noun	Adjective	Verb	Adverb
second childhood	Yes	No	No	No
geezerhood	Yes	No	No	No

As nouns, geezerhood is a hypernym of second childhood; that is, geezerhood is a word with a broader meaning than second childhood:

second childhood: mental infirmity as a consequence of old age; sometimes shown by foolish infatuations
geezerhood: a late time of life

Other hypernyms of second childhood include age, eld, old age, years.

second childhood (noun)	geezerhood (noun)
mental infirmity as a consequence of old age; sometimes shown by foolish infatuations	a late time of life