/'mɪstrɪs; `mɪstrɪs/
n
1 woman in a position of authority or control 有权位的女子; 女主人
*mistress of the situation 控制局面的女人
* She wants to be mistress of her own affairs, ie organize her own life. 她的事情她要自己作主.
* (dated 旧) Is the mistress of the house in? (ie the female head of the household) 女主人在家吗?
* (fig 比喻) Venice was called the `Mistress of the Adriatic'. 威尼斯曾别称｀亚得里亚海的门户＇. Cf 参看 master1 1.
2 female owner of a dog or other animal （狗的或其他动物的）女主人.
3 (esp Brit) female school teacher （中小学的）女教师
*the `French mistress, ie teacher of French (but not necessarily a Frenchwoman) 法语（女）教师（不一定是法国人）
* We've got a new `games mistress (ie one in charge of sport) this year. 今年我校新来了个女的体育教师.
4 woman having an illicit but regular sexual relationship, esp with a married man情妇
*have/keep a mistress 有情妇. Cf 参看 lover 1.5 (arch 古) woman loved and courted by a man; sweetheart （女）情人, 爱人
*O mistress mine! 噢, 我的爱人!
6 (idm 习语) be one's own master/mistress => master1.

n[C]
[Date: 1200-1300; Language: Old French;Origin: maistresse, from maistre; MASTER¹]
a woman that a man has a sexual relationship with, even though he is married to someone else
　The Prince had shocked society by living openly with his mistress.
BrE old-fashioned a female teacher
→master
　the new English mistress
the female owner of a dog, horse etc
→master
old-fashioned the female employer of a servant
→master
　The maid looked nervously at her mistress.
be (a/the) mistress of sth
if a woman is a mistress of something, she is in control of it, highly skilled at it etc
→master
　She appeared to be very much the mistress of the situation.
Mistress
old use used with a woman's family name as a polite way of speaking to her
→master