noun
A person who derives sexual pleasure from inflicting pain or humiliation on others. This is a formal, clinical term; in everyday conversation, サディスト is more common.
加虐性愛者は、相手に苦痛を与えることで性的満足を得る。
A sadist obtains sexual satisfaction by inflicting pain on their partner.
Compound of 加虐 (inflicting harm) + 性愛 (sexual love) + 者 (person). The exact derivation is uncertain; it is a modern clinical term.