The Collaborative International Dictionary of English v.0.48:

Soliloquy \So*lil"o*quy\, n.; pl. Soliloquies. [L.
   soliloquium; solus alone + loqui to speak. See Sole ly, and
   Loquacious.]
   1. The act of talking to one's self; a discourse made by one
      in solitude to one's self; monologue.
      [1913 Webster]

            Lovers are always allowed the comfort of soliloquy.
                                                  --Spectator.
      [1913 Webster]

   2. A written composition, reciting what it is supposed a
      person says to himself.
      [1913 Webster]

            The whole poem is a soliloquy.        --Prior.
      [1913 Webster]

WordNet (r) 3.0 (2006):

soliloquy
    n 1: speech you make to yourself [syn: soliloquy, monologue]
    2: a (usually long) dramatic speech intended to give the
       illusion of unspoken reflections