old maid

An old maid is a woman who has never married, especially one considered past the typical age for marriage.

The term is old-fashioned and often carries a negative connotation of loneliness or undesirability: She feared becoming an old maid like her aunt.

Old maid is also a children's card game where players match pairs and try to avoid being left holding the unmatchable "old maid" card.

The name sometimes extends to anything outdated or left over: Those old maid kernels at the bottom of the popcorn bowl never popped.