Definitions for "Gregorian chant"
Name commonly given to the plainsong of the Catholic church, setting the Latin liturgy. Its connection with Pope Gregory the Great (r. 590-604) is uncertain: much of the music we know comes from manuscripts of about the 10th century.
Also called plainsong or monophonic chant, these sacred Latin pieces were sung in unison by male choirs as part of the Catholic Mass during the Middle Ages. The name "Gregorian" comes from Pope Gregory the Great who collected and catalogued many of these chants. ( Lesson 3)
See chant.