The aim of this article is to look at the region of Europe located between the German and the Russian worlds in the light of the name which was given to it and its borders. How it was mapped, named, defined and delimitated by geographers from the end of the XIXth century up to now ? We have chose to compare the contributions of geographers from both sides of the former Iron Curtain: the French and the Polish ones. The paper discusses the ambiguity in both languages of "Central" (meaning the centre or the middle of an entity), and we analyse why that the expression "Central Europe" was replaced in French Geography by "Median Europe" (Europe médiane), whereas Polish geographers have continued mainly to use the categories "Central" or "Central and Eastern Europe". The mapping of those categories remain unstable in the time, and fuzzy in both geographies, which is a part of the definition of this region.