Gregorian Chant [plainsong]
Gregorian chant [plainsong], comprising not only the Church music of the early Middle Ages, but also later compositions (elaborate melodies for the Ordinary of the Mass, sequences, etc.) written in a similar style down to the sixteenth century and even in modern times. In a stricter sense Gregorian chant means that Roman form of early plain chant as distinguished from the Ambrosian, Gallican, and Mozarabic chants, which were akin to it, but were gradually supplanted by it from the eighth to the eleventh century.