singleton vs ace

singleton and ace both are nouns.

Word	Noun	Adjective	Verb	Adverb
singleton	Yes	No	No	No
ace	Yes	Yes	Yes	No

As nouns, ace is a hypernym of singleton; that is, ace is a word with a broader meaning than singleton:

Other hypernyms of singleton include 1, I, one, single, unity.

singleton (noun)	ace (noun)
the playing card that is the only card in a suit held in a bridge hand as initially dealt	a serve that the receiver is unable to reach
a set containing a single member	one of four playing cards in a deck having a single pip on its face
a single object (as distinguished from a pair)	someone who is dazzlingly skilled in any field
	the smallest whole number or a numeral representing this number

singleton (adjective)	ace (adjective)
	of the highest quality