Entry 1 sense Webster, 1913 Eusebian · Eu·se·bi·an · IPA 01 n. A follower of Eusebius, bishop of Cæsarea, who was a friend and protector of Arius. 1. A follower of Eusebius, bishop of Cæsarea, who was a friend and protector of Arius.(Eccl. Hist.)