Definitionposition of authority, one who rules others or has control, authority, power, or ownership over something.
2. The female head of a household or institution.
3. In Britain, a female schoolteacher or tutor.
4. A woman who has continuing sexual intercourse with and is supported by a man who is not her husband, but more often the husband of another woman.
SYNONYMS: bachelor's wife; canary; columbine; convenient; concubine; courtesan; doxy; fancy woman; fresh bit; jellyroll; kept woman; keptie; lady bird; left-handed wife; leman; paramour; peculiar; secondary wife; side dish; spare rib; stud mare; Sunday girl; unofficial wife; wife in watercolors.
5. More rarely, a sweetheart.
6. In BDSM, a woman owner of a slave; a slavemaster or slavemistress. Mistress is a courtesy title and courtesy titles such as countess, domina; marquesa, lady, mistress, mistresse, princess, and queen, are usually followed by a name. Examples: Mistress Pain; Countess Storm.