a. [ L. epistolaris, fr. epistola: cf. F. épistolaire. ] 1. Pertaining to epistles or letters; suitable to letters and correspondence; as, an epistolary style. [ 1913 Webster ]
2. Contained in letters; carried on by letters. “Epistolary correspondence.” Addison. [ 1913 Webster ]
(adj) written in the form of or carried on by letters or correspondence, Syn. epistolatory, Example:an endless sequence of epistolary love affairs; the epistolatory novel