epistle

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A letter, especially a formal one. See Synonyms at letter.
2. n. A literary composition in the form of letter.
3. n. Bible One of the letters included as a book in the New Testament.
4. n. Bible An excerpt from one of these letters, read as part of a religious service.

Century Dictionary and Cyclopedia

1. n. A written communication directed or sent to a person at a distance; a letter; a letter missive: used particularly in dignified discourse or in speaking of ancient writings: as, the epistles of Paul, of Pliny, or of Cicero.
2. n. [capitalized] In liturgics, one of the eucharistic lessons, taken, with some exceptions, from an epistolary book of the New Testament and read before the gospel. In the early church a lection from the Old Testament, called the prophecy, preceded it, and such a lection is still sometimes used instead of it. In the Greek Church the epistle (called the apostle, as also in the early church) is preceded by the prokeimenon and followed by “Peace to thee” and “Alleluia”; in the Western Church it is preceded by the collects and followed by the Deo gratias, the gradual, tract, or alleluia, with the verse or sequence. It is read in the Greek Church by the anagnost or lector at the holy doors, and in the Western Church by the subdeacon or epistler (in the Roman Catholic Church the celebrant also reciting it in a low voice) at the south side of the altar, that is, at a part of the front of the altar on the celebrant's right as he faces it. Formerly it was read from the ambo (sometimes from a separate or epistle ambo) or pulpit, or from the step of the choir. Sometimes called the lection simply.
3. n. Any kind of harangue or discourse; a communication.
4. To write as a letter; communicate by writing or by an epistle.

Wiktionary

1. n. A letter, or a literary composition in the form of a letter.
2. n. Christianity One of the letters included as a book of the New Testament.
3. v. obsolete To write; to communicate in a letter or by writing.

GNU Webster's 1913

1. n. A writing directed or sent to a person or persons; a written communication; a letter; -- applied usually to formal, didactic, or elegant letters.
2. n. (Eccl.) One of the letters in the New Testament which were addressed to their Christian brethren by Apostles.
3. v. obsolete To write; to communicate in a letter or by writing.

WordNet 3.0

1. n. a book of the New Testament written in the form of letter from an Apostle
2. n. a specially long, formal letter