n.1 formal or joc. a letter, esp. a long one on a serious subject.
2 (Epistle) a any of the letters of the apostles in the New Testament. b an extract from an Epistle read in a church service.
3 a poem or other literary work in the form of a letter or series of letters.
Etymology: ME f. OF f. L epistola f. Gk epistole f. epistello send news (as EPI-, stello send)