oui

language of the south of France in the Middle Ages, the language of the troubadours (Provençal is one of its principal branches), 1660s, from French langue d'oc "speech of the south of France," literally "the language of 'yes,' " from oc, the word used south of the Loire for "yes," which is from Latin hoc "this," which in Vulgar Latin came to mean "yes" (see oui). The name also was given to one of the provinces where it was spoken. Opposed to langue d'oïl, from the way of saying "yes" in the north of France, from Old French oïl (Modern French oui). The langue d'oïl developed into standard Modern French. Related: Languedocian.

Langue d'oc was truer to Latin than Old French or Castilian Spanish were, and had fewer Germanic words. Dante considered it a separate language, and it and the northern French were not always mutually intelligible. Jonathan Sumption's "The Albigensian Crusade" [Faber and Faber, 1978] refers to a court official at Albi "who in 1228 referred to a seal as bearing an inscription in 'French or some other foreign language.'" The French authorities began to repress langue d'oc in 16c.