A woman having power, authority, or ownership; a woman who exercises authority, is chief, etc.; the female head of a family, a school, etc.

A woman well skilled in anything, or having the mastery over it.

A woman regarded with love and devotion; she who has command over one's heart; a beloved object; a sweetheart.

A woman filling the place, but without the rights, of a wife; a woman having an ongoing usually exclusive sexual relationship with a man, who may provide her with financial support in return; a concubine; a loose woman with whom one consorts habitually; as, both his wife and his mistress attended his funeral.

A title of courtesy formerly prefixed to the name of a woman, married or unmarried, but now superseded by the contracted forms, Mrs., for a married, and Miss, for an unmarried, woman.

A married woman; a wife.

( Noun) A woman who engages in entertainment with married men, or a woman having a sexual affair with a married man; or the "female head of a household" whether married to a "male/master of the household" or a single woman, same meaning. The term "Dominant Mistress" refers to a woman who exclusively plays the dominant role in a D/S relationship. In the pop-culture BDSM industry this term is synonymous with dominatrix.

A title of honour for a (female) sexual Dominant that usually denotes either a high level of experience or competence. Also used (voluntarily) as a title of respect for female Dominants that have served the BDSM community as a whole. Alternatively used as a term of endearment for the Domme in a Scene featuring “Mistress/slave” role-playing. Similar titles include Ma'am, Lady, and Momma.

an adulterous woman; a woman who has an ongoing extramarital sexual relationship with a man

a woman schoolteacher (especially one regarded as strict)

a woman master who directs the work of others

a Female owner of slaves or a Woman who dominates and takes control of those who submit to Her

a kept woman, boys

a person who supplements that relationship with my wife, by providing opportunities for intimacy in ways beyond my wife does

Feminine form of Master. Use is optional. It is not unusual for a Mistress to be referred to as "Master".

Name for a woman who takes control in the SM role-play.

A woman in a position of authority who owns slaves, typically the wife of the master.

A dominant woman in a BDSM relationship, dominatrix.

A mistress is a man's long term sexual partner and companion. Historically, the term has denoted a "kept woman", who is maintained in a comfortable (or even lavish) lifestyle by a wealthy man so that she will be available for his sexual pleasure; essentially a kind of highly expensive, single-client prostitute. Today however, it is used primarily to refer to the companion of a man who is married to another woman, in the case of an unmarried man it is usual to speak of a "girlfriend" or "partner."