Sadomasochism is when someone gets sexual pleasure from hurting another person, or from being hurt, or from both. It is a long, rather medical-sounding word. The first half, sado-, comes from sadism (pleasure from hurting); the second half comes from masochism (pleasure from being hurt). Together they name that mix. Though actually, people use it for a range of things: a private sexual habit between adults who both agree, or a general idea of “pain and pleasure mixed.” It is an adult word. You will meet it in news, books, and psychology more than in school textbooks. In real life, many people just say SM — short, easy, and what you will hear. Sadism alone is only the hurting side; masochism alone is only the being-hurt side; this word is the two together.

SM（施虐受虐）。台灣口語幾乎都說 SM；較正式才說虐戀。