old maid

Concise Oxford English Dictionary © 2008 Oxford University Press:
old maid

▶noun

• 1 derogatory a single woman regarded as too old for marriage.

  ■ a prim and fussy person.

• 2 a card game in which players collect pairs and try not to be left with an odd penalty card, typically a queen.

– derivatives
old-maidish adjective.