1. A woman who has a continuing sexual relationship with a man who is married to someone else.
2. A woman in a position of authority, control, or ownership, as the head of a household: "Thirteen years had seen her mistress of Kellynch Hall" (Jane Austen).
a. A woman who owns or keeps an animal: a cat sitting in its mistress's lap.
b. A woman who owns a slave.
4. A woman with ultimate control over something: the mistress of her own mind.
a. A nation or country that has supremacy over others: Great Britain, once the mistress of the seas.
b. Something personified as female that directs or reigns: "my mistress ... the open road" (Robert Louis Stevenson).
6. A woman who has mastered a skill or branch of learning: a mistress of the culinary art.
7. Mistress Used formerly as a courtesy title when speaking to or of a woman.
8. Chiefly British A woman schoolteacher.
[Middle English maistresse, from Old French, feminine of maistre, master, from Latin magister; see MASTER.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2016 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus