n. (pl. -os) a large musical instrument played by pressing down keys on a keyboard and causing hammers to strike metal strings, the vibration from which is stopped by dampers when the keys are released. piano-accordion an accordion with the melody played on a small vertical keyboard like that of a piano. piano organ a mechanical piano constructed like a barrel-organ. piano-player 1 a pianist. 2 a contrivance for playing a piano automatically.
[ It., abbr. of PIANOFORTE ]