What is Epistle?

Epistle definition and meaning on Dictionary terms:
a letter, especially a formal or didactic one; written communication.
(usually initial capital letter) one of the apostolic letters in the New Testament.
(often initial capital letter) an extract, usually from one of the Epistles of the New Testament, forming part of the Eucharistic service in certain churches.


reference: https://www.dictionary.com/browse/epistle