The proper (Latin: proprium) is a part of the Christian liturgy that varies according to the date, either representing an observance within the liturgical year, or of a particular saint or significant event. The term is used in contrast to the ordinary, which is that part of the liturgy that is reasonably constant, or at least selected without regard to date, or to the common, which contains those parts of the liturgy that are common to an entire category of saints, such as apostles or martyrs.
Propers may include hymns and prayers in the canonical hours and in the Eucharist.
See also: Order of Mass § Proprium
The proper of the mass, strictly speaking, consists of the Introit, Gradual, Alleluia or Tract, Sequence, Offertory, and Communion - in other words, all the variable portions of a mass which are spoken or sung by the choir or the people. These are sometimes called the "minor propers" to distinguish them from the collect, secret, postcommunion, and readings - in other words, all the variable portions of a mass which are spoken or sung by the priest or other attendants, such as a lector or deacon. In Roman Catholic and Anglo-Catholic practice, there is a moveable portion of the service that, strictly speaking, does not form part of the proper known as the Accentus. Portions of the Accentus are often referred to as part of the "proper" if they satisfy the criteria of changing by date (such as the Preface and Epistle).
The propers are numerous and are drawn from a large collection of liturgical books, including the Euchologion, Horologion, Octoechos, and Menaion. During the ten-week period of Lent, propers are also drawn from the Lenten Triodion, and during the eight weeks after Easter, from the Pentecostarion. There are certain other books of propers as well for more specific applications, such as the Theotokarion.
The Typikon describes how the propers are to be used—and when commemorations overlap, how the propers are to be combined and which propers may suppress others. The following table outlines the basic propers for the services of the Byzantine Rite outside of Great Lent and Bright Week.