How do you spell Trinitarian

Available Definitions:
1)  a. - Of or pertaining to the Trinity, the doctrine of the Trinity, or believers in that doctrine.
2)  n. - One who believes in the doctrine of the Trinity.
3)  n. - One of a monastic order founded in Rome in 1198 by St. John of Matha, and an old French hermit, Felix of Valois, for the purpose of redeeming Christian captives from the Mohammedans.