International audienceFrom an ontological point of view, the existence of a word is the evidence for the necessity of an underlying cognitive concept. We will discuss the notion of connexity through three different words. The etymology of border, frontier and limit leads to attribute them different models of let's say ''boundary'': respectively the boundary belongs to only one object, is shared by both or belongs to none (hence is an object by itself). We compare this approach to several axiomatic (mereological) definitions of connexity: weak connexity, fiat and bona fide boundaries (cf. Asher, Couclelis, Varzi ...). The target application is a study on urban development and ''metropolisation'' shapes observed through remote sensing. The bo...