Sadomasochism is the giving or receiving of pleasure from acts involving the receipt or infliction of pain or humiliation. Practitioners of sadomasochism may seek sexual gratification from their acts. While the terms sadist and masochist refer respectively to one who enjoys giving and receiving pain, practitioners of sadomasochism may switch between activity and passivity.

The abbreviation S&M is often used for sadomasochism, although practitioners themselves normally remove the ampersand and use the acronym S-M or SM or S/M when written throughout the literature. Sadomasochism is not considered a clinical paraphilia unless such practices lead to clinically significant distress or impairment for a diagnosis. Similarly, sexual sadism within the context of mutual consent, generally known under the heading BDSM, is distinguished from non-consensual acts of sexual violence or aggression.

The term sadomasochism is used in a variety of different ways. It can refer to cruel individuals or those who brought misfortunes onto themselves and psychiatrists define it as pathological. However, recent research suggests that sadomasochism is mostly simply a sexual interest, and not a pathological symptom of past abuse, or a sexual problem, and that people with sadomasochistic sexual interest are in general neither damaged nor dangerous.