Mistress

UK: 'mistress', 'Mistress': /ˈmɪstrɪs/

US: /ˈmɪstrɪs/

US: (mis′tris)

Collins Concise English Dictionary © HarperCollins Publishers::

Mistress / ˈmɪstrɪs/ noun

1. an archaic or dialect title equivalent to Mrs

WordReference Random House Learner's Dictionary of American English © 2025

mis•tress /ˈmɪstrɪs/   n. [countable]

1. a woman who has authority, esp. the female head of a household:
   The servant did whatever the mistress of the house ordered.
2. a woman who has a continuing sexual relationship with a man not married to her:
   He had mistresses in several cities.
3. a woman who has control of something:
   the mistress of a great fortune.
4. something thought of as feminine that has control:
   [sometimes: Mistress] Great Britain, mistress of the seas.
5. [Brit.] a female schoolteacher;
   schoolmistress.

WordReference Random House Unabridged Dictionary of American English © 2025

mis•tress  (mis′tris), n. 

1. a woman who has authority, control, or power, esp. the female head of a household, institution, or other establishment.
2. a woman employing, or in authority over, servants or attendants.
3. a female owner of an animal, or formerly, a slave.
4. a woman who has the power of controlling or disposing of something at her own pleasure:
   mistress of a great fortune.
5. (sometimes cap.) something regarded as feminine that has control or supremacy:
   Great Britain, the mistress of the seas.
6. a women who is skilled in something, as an occupation or art.
7. a woman who has a continuing, extramarital sexual relationship with one man, esp. a man who, in return for an exclusive and continuing liaison, provides her with financial support.
8. [Brit.] a female schoolteacher;
   schoolmistress.
9. (cap.) a term of address in former use and corresponding to Mrs., Miss, or Ms.
10. [Archaic.] sweetheart.

• Middle French, Old French, equivalent. to maistre master + -esse -ess
• Middle English maistresse 1275–1325

mis′tressed, adj. 
mis′tress-ship′, n. 
Usage

See -ess. 

Collins Concise English Dictionary © HarperCollins Publishers::

mistress / ˈmɪstrɪs/ noun

1. a woman in a position of authority, ownership, or control, such as the head of a household
2. a woman or female personification having control over something specified: she was mistress of her own destiny
3. a woman who has a continuing extramarital sexual relationship with a man
4. 
   short for schoolmistress
5. an archaic or dialect word for sweetheart

Etymology: 14th Century: from Old French; see master, -ess