Apostolos
An apostolos or epistle is a writing directed or sent to a person or group of persons, usually a letter and a very formal, often didactic and elegant one. The letters from Apostles to Christians in the New Testament are often referred to as epistles.
In the context of the Divine Liturgy or other liturgical service, epistle may refer more specifically to a particular passage from a New Testament epistle that is scheduled to be read on a certain day or at a certain occasion, and the Apostolos is the liturgical book containing the various epistle readings as they appointed by the lectionary.
