The Collaborative International Dictionary of English v.0.48:

Phonograph \Pho"no*graph\, n. [Phono- + -graph.]
   1. A character or symbol used to represent a sound, esp. one
      used in phonography. [archaic]
      [1913 Webster]

   2. (Physics) An instrument for the mechanical registration
      and reproduction of audible sounds, as articulate speech,
      etc. An early simple version consisted of a rotating
      cylinder or disk covered with some material easily
      indented, as tinfoil, wax, paraffin, etc., above which is
      a thin plate carrying a stylus. As the plate vibrates
      under the influence of a sound, the stylus makes minute
      indentations or undulations in the soft material, and
      these, when the cylinder or disk is again turned, set the
      plate in vibration, and reproduce the sound. Modern
      versions use electronic circuitry and various more stable
      recording media to record sound more accurately.
      [1913 Webster + PJC]

   3. An instrument for reproducing sounds, especially music,
      previously recorded on a plastic cylinder or disk as a
      pattern of bumps or wiggles in a groove. A needle (stylus)
      held in the groove is made to vibrate by motion (rotation)
      of the recording, and the vibrations caused by the bumps
      and wiggles are transmitted directly to a membrane, or
      first transduced into electrical impulses and sent to an
      electronic amplifier circuit, thereby reproducing with
      greater or less fidelity the original sounds. A phonograph
      which is equipped with electronics enabling the playback
      of sound with high fidelity to the original is often
      called a hi-fi.

   Note: In the 1990's such devices are beginning to be replaced
         in many homes by compact disk players; the production
         of plastic recordings of music for playback on a
         phonograph has almost ceased for entertainment
         purposes.
         [PJC]

WordNet (r) 3.0 (2006):

phonograph
    n 1: machine in which rotating records cause a stylus to vibrate
         and the vibrations are amplified acoustically or
         electronically [syn: record player, phonograph]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "phonograph":
   Gramophone, PA, PA system, Victrola, audio sound system,
   audiophile, binaural system, bitch box, bullhorn, cartridge,
   ceramic pickup, changer, crystal pickup,
   derived four-channel system, discrete four-channel system,
   four-channel stereo system, hi-fi, hi-fi fan, high-fidelity,
   intercom, intercommunication system, jukebox, magnetic pickup,
   monaural system, mono, needle, nickelodeon, photoelectric pickup,
   pickup, public-address system, quadraphonic sound system,
   radio-phonograph combination, record changer, record player,
   sound reproduction system, sound truck, squawk box, stereo, stylus,
   system, tape deck, tape recorder, tone arm,
   transcription turntable, turntable



The Devil's Dictionary (1881-1906):

PHONOGRAPH, n.  An irritating toy that restores life to dead noises.