Know how to use "fewer" and "less"? Find out.
(from Italian appoggiare, "to lean"), in music, an ornamental note of long or short duration that temporarily displaces, and subsequently resolves into, a main note, usually by stepwise motion. During the Renaissance and early Baroque, the appoggiatura was of moderate length, averaging one-third of the main note, and was more in the nature of a melodic than a harmonic ornament. By the time of Johann Sebastian Bach (1685-1750), appoggiaturas were divided into two species: the short, which borrows an inconsiderable length from its main note and therefore has little effect on the harmony; and the long, which takes half or more of the length of its main note and therefore substantially affects the harmony, creating a dissonance that then resolves, on the main note, to a consonance. Because its purpose was mainly expressive, whether in purely melodic or harmonic terms, the typical appoggiatura in 17th- and 18th-century music occurred on the beat, rather than before it, "leaning" on the principal note, as suggested by the term's derivation