"language of medieval France south of the Loire," 1660s, from French langue d'oc "speech of the south of France," literally "the language of 'yes,' " from oc the word used for "yes" in southern France, from Latin hoc "this;" as opposed to langue d'oïl, from the way of saying "yes" in the north of France (Modern French oui); each from a different word in Latin phrase hoc ille (fecit) "this he (did)." The langue d'oïl has developed into standard Modern French.