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. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.