In law, an unmarried woman; specifically, a single woman, including those who have been married, but whose marriage has been dissolved by death or divorce, and, for most purposes, those women who are judicially separated from their husbands.

The opposite is feme covert, "a married woman".

In old English law, a married woman, who, by the custom of London, trades on her own account, independently of her husband; so called because, with respect to her trading, she is the same as a feme sole.

The term is also applied to women who have been deserted by their husbands, who do business as femes sole.