The analysis of Internal Localization Nouns (ILNs) is considered here in the framework of the general studies on part-whole relations or meronomies. Data from Basque and French indicate that these lexical elements have semantic and syntactic properties which clearly differentiate them from other meronomic relations, in particular from component nouns usually used for designating functional parts of spatial entities. Beyond a strict opposition, it seems that ILNs diachronicly derive from component nouns and acquire, during such an evolution, semantic properties which make them real relational markers of spatial localization. More generally, this study on ILNs of Basque and French seems to indicate that there exists a general concept of location which plays a great part in the linguistic and cognitive classification of spatial entities and underlies the functioning of several linguistic markers of space.