Meaning

noun a keyboard instrument that is played by depressing keys that cause hammers to strike tuned strings and produce sounds

noun (music) low loudness

adjective used chiefly as a direction or description in music

originClipping of pianoforte, from Italian pianoforte, from piano (“soft”) + forte (“strong”). So named because it could produce a wide range of varied volumes note-by-note, in contrast to older keyboard instruments, notably the harpsichord. Doublet of llano, plain, and plane.

Etymology from Wiktionary, CC BY-SA 3.0