Tetrarch. Properly, the sovereign or governor of the fourth part of a country. Matthew 14:1; Luke 3:1; Luke 9:7; Acts 13:1. The title was, however, often applied to any one, who governed a Roman province, of whatever size. The title of king was, sometimes, assigned to a tetrarch. Matthew 14:9; Mark 6:14; Mark 6:22.