old maid vs also-ran

old maid and also-ran both are nouns.

Word	Noun	Adjective	Verb	Adverb
old maid	Yes	No	No	No
also-ran	Yes	No	No	No

As nouns, also-ran is a hypernym of old maid; that is, also-ran is a word with a broader meaning than old maid:

Other hypernyms of old maid include loser.

old maid (noun)	also-ran (noun)
a card game using a pack of cards from which one queen has been removed; players match cards and the player holding the unmatched queen at the end of the game is the loser (or `old maid')	a contestant who loses the contest
an elderly unmarried woman
the loser in a game of old maid
commonly cultivated Old World woody herb having large pinkish to red flowers
any of various plants of the genus Zinnia cultivated for their variously and brightly colored flower heads