Gregorian

Gregorian is an adjective and a proper noun derived from the Latin Gregorius, meaning belonging to Gregory. It is most often used of traditions and things associated with Saint Gregory the Great or with persons named Gregory. The term commonly denotes two major Western traditions, though it appears in other contexts as well: the Gregorian calendar and Gregorian chant.

Gregorian calendar: Introduced by Pope Gregory XIII in 1582 as a reform of the Julian calendar, the Gregorian calendar shortened the drift of the year by skipping 10 days and by a refined rule for leap years: years divisible by 4 are leap years except those divisible by 100, unless divisible by 400. The reform improved alignment with the solar year and the seasons. Adoption spread gradually across Europe and the rest of the world in subsequent centuries; today the Gregorian calendar is the internationally accepted civil calendar, with minor local variations in historical practices.

Gregorian chant: A tradition of Western liturgical chant that developed in the early Middle Ages. It is traditionally linked to the organizing efforts of Pope Gregory I, though scholarly evidence for a direct attribution is limited. Gregorian chant is typically monophonic, sung in Latin, and centered in the Roman Rite. The music was transmitted orally for centuries and later notated, forming a foundational part of Western plainchant and early medieval musical notation.

Other uses: The term also appears in popular culture and music. For example, Gregorian is the name of a German-based group formed in the 1990s that performs contemporary songs in a style inspired by Latin liturgical chant. The word itself continues to be used in surnames and institutional names connected to Gregory.