Dominican (1)
"Black friar," 1630s, from Latin form of the name of Domingo de Guzman (Santo Domingo), founder of the order of preaching friars. His name, like Italian form Dominic, is from Latin dominicus "pertaining to a lord."
Dominican (2)
"native or inhabitant of the Dominican Republic," 1853, from the Caribbean island of Dominica, home of the nation, so named 1493, from Latin (dies) dominica "Sunday," the day of the week on which the island was discovered.