👉 Gregarianism, also known as Gregorianization or Gregorianization of Latin, is a historical process that occurred in the 19th century when the Roman Catholic Church began to adopt the Gregorian calendar. This calendar was adopted after it had been used for many centuries by the Eastern Orthodox Church, which was not yet adopting the Gregorian calendar. The Gregorian calendar was introduced as an alternative to the Julian calendar, which had been in use since 1582. The