Dominicans, a religious order of preaching friars, founded at Toulouse in 1215 by St. Dominic, to aid in the conversion of the heretic Albigenses to the faith, and finally established as the order whose special charge it was to guard the orthodoxy of the Church. The order was known by the name Black Friars in England, from their dress; and Jacobins in France, from the street of Paris in which they had their head-quarters.