old maid

1. N-COUNT People sometimes refer to an old or middle-aged woman as an old maid when she has never married and they think that it is unlikely that she ever will marry. This use could cause offence. (冒犯的)老姑娘[老式]

Alex is too young to be already thinking of herself as an old maid. 阿历克丝认为自己是个老姑娘的想法还太早了点。