Dux

Dux (/dʌks, dʊks/, pl.: ducēs) is Latin for "leader" (from the noun dux, ducis, "leader, general") and later for duke and its variant forms (doge, duce, etc.). During the Roman Republic and for the first centuries of the Roman Empire, dux could refer to anyone who commanded troops, both Roman generals and foreign leaders, but was not a formal military rank.