(pē·an′ō) noun plural ·an·os
A stringed musical instrument having felt–covered hammers, operated from a manual keyboard, which strike upon steel wires to produce the tones; a pianoforte.
—concert grand piano The largest size of grand piano, used for concert performances.
—grand piano A horizontal, harp–shaped piano, having three or more strings to each note, and action without springs.
—square piano A piano having a horizontal rectangular case and horizontally strung wires.
—upright piano A piano in which the case is upright, with the strings vertical and overstrung to save space. [<Ital., short for pianoforte PIANOFORTE]

(pē·ä′nō, Ital. pyä′nō) adverb
With slight force; softly: a direction to a singer or player of a musical instrument: abbr. p.
—adjective Performed or to be performed with slight force; soft: a piano passage.
—noun A passage of music rendered softly and lightly. [<Ital. <L planus flat, soft (of sound)]