masc. proper name, from Late Latin Hilarius, literally "cheerful," from Latin hilaris (see hilarity). The name was more popular in France than in England. The woman's name (Middle English Hillaria) seems to be merged with this from Eulalia, name of the patron saint of Barcelona, a Latinization of Greek eulalos "sweetly speaking." The Hilary sessions of British High Court and universities (1577) are from St. Hilarius, Bishop of Poitiers, obit. C.E. 368, whose feast day is Jan. 13.