from Latin Hibernia, the Roman name for Ireland, also in forms Iverna, Juverna, Ierne, etc., all ultimately from Old Celtic *Iveriu "Ireland" (see Irish (n.)). This particular form of the name was altered in Latin as though it meant "land of winter" (see hibernation).
-ian
variant of suffix -an (q.v.), with connective -i-. From Latin -ianus, in which the -i- originally was from the stem of the word being attached but later came to be felt as connective. In Middle English frequently it was -ien, via French.