Maundy Thursday uses the term "Maundy Thursday" to refer to the holy day in its official sources. In the Eastern Orthodox Church, the name for the holy day is, in the Byzantine Rite, "Great and Holy Thursday" or "Holy Thursday", and in Western Rite Orthodoxy "Maundy Thursday", "Holy Thursday" or both. The Coptic Orthodox Church uses the term "Covenant Thursday" or "Thursday of the Covenant". In the Maronite Church and the Syriac Orthodox Church, the name is "Thursday of Mysteries". "Maundy Thursday" is the official name of the day in the civil legislation of England and the Philippines. The day has also
Adoption of the Gregorian calendar 12 days, only 11 were skipped, and the day of the week was repeated on successive days, because at the same time the International Date Line was moved, from following Alaska's eastern border with Canada to following its new western border, now with Russia. Many of the countries of eastern Europe were Eastern Orthodox or Islamic and adopted the Gregorian calendar much later than western Christian countries. Roman Catholic countries such as the Polish–Lithuanian Commonwealth adopted the "new style" (N.S.) Gregorian calendar in 1582 (switched back in 1795 after Third Partition of Poland), but the switch to the Gregorian calendar