APOSTLE, in the Greek liturgy, is particularly used for a book containing the epistles of St. Paul, printed in the order wherein they are to be read in churches, through the course of the year. Another book of the like kind, containing the Gospels, is called Ευαγγέλιον, Gospel.—The apostle, of late days, has also contained the other canonical epistles, the acts of the Apostles, and the Revelation. Hence it is also called Acts of the Apostles, Πράξεις; that being the first book in it.