Masturbate

google

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mid 19th century: from Latin masturbat- ‘masturbated’, from the verb masturbari, of unknown origin.

wiktionary

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From Latin masturbārī. Further derivation uncertain; see masturbor for more.

etymonline

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masturbate (v.)

"produce an orgasm by stimulation of the genitals," 1839, a back-formation from masturbation, or else from Latin masturbatus, past participle of masturbari. The earlier form was mastuprate (17c.), for which see masturbation. Transitive use is by 1970. Related: Masturbated; masturbating.