NOUN (1)

1. adherent of Unitarianism;


ADJECTIVE (1)

1. of or relating to or characterizing Unitarianism;

The Collaborative International Dictionary of English v.0.48:

Unitarian \U`ni*ta"ri*an\, a.
   Of or pertaining to Unitarians, or their doctrines.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Unitarian \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.
      [1913 Webster]

   2. One who rejects the principle of dualism.
      [1913 Webster]

   3. A monotheist. [R.] --Fleming.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Unitarian
    adj 1: of or relating to or characterizing Unitarianism
    n 1: adherent of Unitarianism

The Devil's Dictionary (1881-1906):

UNITARIAN, n.  One who denies the divinity of a Trinitarian.