Octave in liturgical usage has two senses. In the first sense, it is the eighth day following a major feast (counting the feast itself as the first day), particularly in the Catholic, Eastern Orthodox and Anglican liturgical calendars. In the late Middle Ages the second sense of octave developed as an eight-day festival with a specific liturgy. The Forum for European-Australian Science and Technology Cooperation (FEAST) is a non-government organisation aimed at highlighting and developing collaborative research activities between Europe (European countries and the European Union) and Australia. ... Eastern Orthodoxy (also called Greek Orthodoxy and Russian Orthodoxy) is a Christian tradition which represents the majority of Eastern Christianity. ... The term Anglican describes those people and churches following the religious traditions of the Church of England, especially following the Reformation. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... A liturgy is the customary public worship of a religious group, according to their particular traditions. ...

Western usage

The term is used in both senses today. In the former sense the Octave of Christmas among the Western churches always falls on January 1st and in the Catholic Church is the Solemnity of Mary, Mother of God, traditionally also celebrated as the Circumcision of Jesus, a holy day of obligation in many countries. Until 1955, the Roman Catholic calendar had many octaves, including the Immaculate Conception, Saint Joseph, Ss. Peter and Paul, Corpus Christi, the Sacred Heart, the Assumption, and All Saints, as well as, locally, the patron saint of a particular nation, diocese, or church, but all except Christmas, Easter, and Pentecost were suppressed. Christmas is an annual holiday that celebrates the birth of Jesus. ... The Solemnity of Mary, Mother of God also known as the Solemnity of the Holy Mother of God is a Christian feast celebrated on January 1 on the Roman Catholic liturgical calendar. ... The Feast of the Circumcision of Our Lord is a feast day formerly celebrated by the Roman Catholic Church on 1 January as a holy day of obligation (a day on which Catholics must attend Mass). ... In the Roman Catholic Church, the Holy Days of Obligation are the days, other than Sundays, on which the faithful are required to attend Mass. ... Mary, mother of Jesus as the Immaculate Conception. ... For other uses, see Saint Joseph (disambiguation). ... Corpus Christi celebrations in Antigua Guatemala, 14 June, 1979 Corpus Christi (Latin: Body of Christ) in Catholicism is a religious feast celebrated by Roman Catholics on the eighth Thursday after Easter, i. ... Typical illustration of the Sacred Heart of Jesus Christ The Sacred Heart is a religious devotion to Jesus physical heart. ... Look up assumption in Wiktionary, the free dictionary. ... The festival of All Saints, also sometimes known as All Saints Day, All Hallows or Hallowmas (hallows meaning saints, and mas meaning Mass), is a feast celebrated in the honour of all the saints, known and unknown. ... Saint Quentin is the patron saint of locksmiths and is also invoked against coughs and sneezes. ... Christmas is an annual holiday that celebrates the birth of Jesus. ... Easter, the Sunday of the Resurrection, Pascha, or Resurrection Day, is the most important religious feast of the Christian liturgical year, observed at some point between late March and late April each year (early April to early May in Eastern Christianity), following the cycle of the moon. ... The Descent of the Holy Spirit in a 15th century illuminated manuscript. ...

In the second sense, that is an eight-day celebration, the term is most commonly used today to refer to the Octave of Easter, the week (and particularly the Sunday) following Easter Sunday, which is the most vividly celebrated octave in the Catholic liturgical year. Each of the days in the Octave of Easter is celebrated with the rites of Easter Sunday, a period sometimes referred to as Easter Week, or the Week of Sundays. The Sunday following Easter Sunday is also called the Octave of Easter, meaning "the eighth day." The Octave of Easter, formerly know as Low Sunday (also known as , or Quasimodo Sunday) is the first Sunday after Easter. ... Eastertide, or the Easter Season, begins on Easter Day and continues until Pentecost in the Christian liturgical calendar, thus spanning a total of seven weeks. ... The Octave of Easter, formerly know as Low Sunday (also known as , or Quasimodo Sunday) is the first Sunday after Easter. ...

Eastern Christian usage

Main article: Afterfeast

Among the Eastern Orthodox and Eastern Catholic Churches, what in the West would be called an Octave is referred to as an Afterfeast. The celebration of the Great Feasts of the church year are extended for a number days, depending upon the particular Feast. Each day of an Afterfeast will have particular hymns assigned to it, continuing the theme of the Feast being celebrated. An Afterfeast is a period of celebration attached to one of the Great Feasts celebrated by the Eastern Orthodox and Eastern Catholic Churches (roughly equivalent to what in the West would be called an Octave). ... The Eastern Catholic Churches are autonomous particular Churches in full communion with the Pope of Rome. ... The feast of the Resurrection of Jesus, called Easter or Pascha, is the greatest of the feasts of the Eastern Orthodox Church. ... The liturgical year, also known as the Christian year, consists of the cycle of liturgical seasons in some Christian churches which determines when Feasts, Memorials, Commemorations, and Solemnities are to be observed and which portions of Scripture are to be read. ...

Most of these Great Feasts also have a day or more of preparation called a Forefeast (those Feasts that are on the moveable Paschal Cycle do not have Forefeasts). Forefeasts and Afterfeasts will affect the structure of the services during the Canonical Hours. Canonical hours are ancient divisions of time, developed by the Christian Church, serving as increments between the prescribed prayers of the daily round. ...

The last day of an Afterfeast is called the Apodosis (lit. "giving-back") of the Feast. On the Apodosis, most of the hymns that were chanted on the first day of the Feast are repeated. On the Apodosis of Feasts of the Theotokos, the Epistle and Gospel of the Feast are repeated again at the Divine Liturgy. Theotokos of Kazan Theotokos (Greek: , translit. ... The Divine Liturgy is the common term for the Eucharistic service of the Byzantine tradition of Christian liturgy. ...