epistolary (adj.)youdaoicibaDictYouDict[epistolary 词源字典]
1650s, from French épistolaire, from Late Latin epistolarius "of or belonging to letters," from Latin epistola "a letter, a message" (see epistle). In Middle English as a noun (early 15c.), "book containing epistles read in the Mass," from Medieval Latin epistolarium.[epistolary etymology, epistolary origin, 英语词源]