What's the "een" in Halloween?
1818, agent noun from Latin source of masturbate (q.v.). Related: Masturbatory.
1839, back-formation from masturbation, or else from Latin masturbatus, past participle of masturbari. Related: Masturbated; masturbating.
masturbate mas·tur·bate (mās'tər-bāt')v. mas·tur·bat·ed, mas·tur·bat·ing, mas·tur·bates To perform an act of masturbation.