<p><strong>Adjective:</strong></p><ul><li>Believing in or adhering to the doctrine of the Trinity.</li><li>Pertaining to Trinitarians, or believers in the doctrine of the Trinity.</li><li>Belonging or pertaining to the religious order of Trinitarians.</li><li>Of or relating to the Trinity.</li><li>(lowercase) Forming a trinity; threefold; triple.</li></ul><p><strong>Noun:</strong></p><ul><li>A person who believes in the doctrine of the Trinity.</li><li>A member of the “Order of the Holy Trinity,” a religious order founded in 1198 to redeem Christian captives of the Muslims.</li></ul>