old vs dandy

old and dandy both are nouns.

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

As adjectives, old and dandy are synonyms defined as:

Other synonyms of old include bang-up, bully, corking, cracking, great, groovy, keen, neat, nifty, not bad, peachy, slap-up, smashing, swell.

old (noun)	dandy (noun)
past times	a sailing vessel with two masts; a small mizzen is aft of the rudderpost
	a man who is much concerned with his dress and appearance

old (adjective)	dandy (adjective)
of long duration; not new	excellent
(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