They share many common linguistic features. One of these is that "Oïl" (pronounced [wil], or [wi] as in modern French "oui"), was the ancestor of the word for "yes" used in all the Oïl languages ("oc" was and still is the word used in territories to the south, and that is why the Occitan language is also called "langue d'oc" (literal English translation: "language of yes")).