The Collaborative International Dictionary
masturbating
masturbate \masturbate\ v. i. [imp. & p. p. masturbated; p. pr. & vb. n. masturbating.] To achieve sexual gratification by stimulating one's own sexual organs, without the aid of a partner; -- typically to the point of orgasm. -- masturbator, n.
Syn: wank, she-bop, jack off, jerk off, whack off, beat the meat.
Wiktionary
masturbating
vb. (present participle of masturbate English)