In a BDSM scene, a mistress is a female dominant, or dominatrix, in a top/bottom relationship. The term is the female version of the term “master,” which refers to a male dominant. Consenting male and female submissives may be under the control of a mistress, who will often require that they perform any tasks she requests, including sexual activities. If a submissive is disobedient or does not please a mistress, the submissive may be punished.
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In BDSM literature, dominant terms, including “mistress” and “master,” are capitalized when written, while submissive terms, like “slave,” are not. The same is true when writing a dominant or submissive’s given name. This is done out of respect and honor for the dominant.