Source : Webster's Revised Unabridged Dictionary (1913)

Monologue \Mon"o*logue\, n. [F. monologue, Gr. ? speaking alone;
   mo`nos alone, single, sole + ? speech, discourse, ? to speak.
   See {Legend}.]
   1. A speech uttered by a person alone; soliloquy; also, talk
      or discourse in company, in the strain of a soliloquy; as,
      an account in monologue. --Dryden.

   2. A dramatic composition for a single performer.

Source : WordNet®

monologue
     n 1: speech you make to yourself [syn: {soliloquy}]
     2: a long utterance by one person (especially one that prevents
        others from participating in the conversation)
     3: a (usually long) dramatic speech by a single actor