French, like all other languages, is full of synonyms and slang words (argot) that native speakers tend to use when speaking amongst themselves. Many common French words taught to us in classrooms or textbooks are in fact rarely used by native speakers, and are replaced by synonyms or slang ...
Yes the Rhineland is the the west of Germany this is exactly why its demilitarisation made wars in the east impossible if France sought to intervene as was required under the French-Polish treaty, as France could easily invade Germany across an undefended Rhine, read Churchill on this. ...