Gregorian

adj. of or pertaining to any of the popes named Gregory (especially Gregory I and Gregory XIII); of or pertaining to the Gregorian calendar

Gregorian might refer to:Gregorian calendarGregorian chantGregorian reformGregorian (band)Gregorian University, RomeBrotherhood of Saint GregoryGregorian telescopeThe Armenian Apostolic Church is sometimes called the Gregorian Church
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Adjective
1. of or relating to Pope Gregory I or to the plainsong chants of the Roman Catholic Church
(pertainym) Gregory, Gregory I, Saint Gregory I, St. Gregory I, Gregory the Great
2. of or relating to Pope Gregory XIII or the calendar he introduced in 1582
(pertainym) Gregory, Gregory VII, Hildebrand

(a.)
Pertaining to, or originated by, some person named Gregory, especially one of the popes of that name.
  

Gregorian