Dictionary.net

Pleasure derived from being physically or psychologically abused, whether inflicted by oneself or by others. Masochism includes sexual masochism.

A form of sexual perversion, the subject of which receives sexual gratification from injury (especially flagellation) or the thought of injury inflicted upon himself. Hence, Masochist, one affected with m. Cf. Sadism.

Sexual perversion with enjoyment of being cruelly treated.