Epistle

Webster's Dictionary of the English Language

·vt To Write; to communicate in a letter or by writing.

II. Epistle ·noun One of the letters in the New Testament which were addressed to their Christian brethren by Apostles.

III. Epistle ·noun A writing directed or sent to a person or persons; a written communication; a letter;

— applied usually to formal, didactic, or elegant letters.