player piano

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A mechanically operated piano, especially a pedal-operated or motor-driven piano using pneumatic suction to move the keys in correspondence to the perforations on a turning piano roll.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun music An acoustic piano which is automatically played (mechanically).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a mechanically operated piano that uses a roll of perforated paper to activate the keys