The Collaborative International Dictionary of English v.0.48:

Self-abuse \Self`-abuse"\, n.
   1. The abuse of one's own self, powers, or faculties.
      [1913 Webster]

   2. Self-deception; delusion. [Obs.] --Shak.
      [1913 Webster]

   3. Masturbation; onanism; self-pollution.
      [1913 Webster]

WordNet (r) 3.0 (2006):

self-abuse
    n 1: manual stimulation of your own genital organ for sexual
         pleasure [syn: self-stimulation, self-abuse]