Pertaining to Arius, a presbyter of the church of Alexandria, in the fourth century, or to the doctrines of Arius, who held Christ to be inferior to God the Father in nature and dignity, though the first and noblest of all created beings. Mosheim. [1913 Webster]
Arian, n. & adj.
--n. an adherent of the doctrine of Arius of Alexandria (4th c.), who denied the divinity of Christ.
--adj. of or concerning this doctrine.