As a Noun: 1. Messages written on pieces of paper and sent through the mail. English = letters, mail, correspondence. 2. One of the books in the New Testament which were originally written as letters to the early Christians by the apostles. English = Epistle. As a Verb or Adjective: 1. To send or receive messages written on pieces of paper and sent through the mail; send or get mail; send or receive correspondence; notify by mail or post.