hoary vs old

hoary is not a noun while old is a noun.

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

hoary (noun)	old (noun)
	past times

hoary (adjective)	old (adjective)
covered with fine whitish hairs or down	of long duration; not new
ancient	(used especially of persons) having lived for a relatively long time or attained a specific age
showing characteristics of age, especially having grey or white hair	skilled through long experience
	(used for emphasis) very familiar
	excellent
	just preceding something else in time or order
	belonging to some prior time