sexagenarian vs old

sexagenarian and old both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexagenarian	Yes	Yes	No	No
old	Yes	Yes	No	No

sexagenarian (noun)	old (noun)
someone whose age is in the sixties	past times

sexagenarian (adjective)	old (adjective)
being from 60 to 69 years old	of long duration; not new
	(used especially of persons) having lived for a relatively long time or attained a specific age
	skilled through long experience
	(used for emphasis) very familiar
	excellent
	just preceding something else in time or order
	belonging to some prior time