U′ni‐ta″ri‐an (?), n. [Cf. F. unitaire, unitairien, NL. unitarius. See Unity.] 1. (Theol.) One who denies the doctrine of the Trinity, believing that God exists only in one person; a unipersonalist; also, one of a denomination of Christians holding this belief.
2. One who rejects the principle of dualism.
3. A monotheist. Fleming.