mistress

Etymology

From Middle English maistresse, from Old French maistresse (whence French maîtresse), feminine of maistre (“master”). By surface analysis, mist(e)r + -ess.

noun

1. A woman, specifically one with great control, authority or ownership
   male equivalent: master
   She was the mistress of the estate-mansion, and owned the horses.
2. A female teacher
   male equivalent: master
   games mistress
3. The other woman in an extramarital relationship, generally including sexual relations
4. A dominatrix
   male equivalent: master
   As part of BDSM play they can enhance the domineering tread of a mistress or hobble the steps of a slave. 2006, Amelia May Kingston, The Triumph of Hope, page 376
5. A woman well skilled in anything, or having the mastery over it
6. a woman regarded with love and devotion; a sweetheart
7. (Scotland) A married woman; a wife
8. (obsolete) The jack in the game of bowls
   She took a bowl, drew up her skirt with her left hand, and rolled the weighted ball with a deft motion. It lightly kissed the mistress and stopped a few inches away. 2001, Paul Hemenway Altrocchi, Most Greatly Lived
9. A female companion to a master (a man with control, authority or ownership)
10. female equivalent of master
11. female equivalent of mister

verb

1. (transitive, rare) Of a woman: to master; to learn or develop to a high degree of proficiency.
   These films give a glimpse of women on the way to mistressing their own destiny. 2013, Andrea Khalil, North African Cinema in a Global Context: Through the Lens of Diaspora
2. (intransitive) To act or take the role of a mistress.
   […] housewifery, maternity, charity, the life conventual, the chatter of a court, the mistressing of a great house […] 1905, Samuel Rutherford Crockett, Maid Margaret of Galloway