masturbation

from WordNet (r) 3.0 (2006)

masturbation
    n 1: manual stimulation of the genital organs (of yourself or
         another) for sexual pleasure [syn: {masturbation},
         {onanism}]

from The Collaborative International Dictionary of English v.0.48

masturbation \mas`tur*ba"tion\, n. [L. masturbatus, p. p. of
   masturbari to practice onanism: cf. F. masturbation.]
   The act of masturbating; sexual self-gratification; onanism.
   [1913 Webster]