The present paper is an attempt to describe a particular semantic domain in Thai, that of local relations, in terms of a gradual interconnection of what traditional descriptions usually regard as distinct and isolated categories. It is based on the well-known observation that isolating languages like Thai typically display a high degree of 'multifunctionality', or else of syntactic 'versatility' of very many lexical items. […] The semantic area studied in the following pages yields a clear systematic interconnection of three different categories, viz. that of nouns – as the focal instance of maximum syntactic independence –, that of verbs – as, conversely, the focal instance of maximally relational concepts –, and, as an intermediary category between these two, that of prepositions which the system lexically feeds from both these opposite ends. The examples given in the course of this paper have been obtained from published grammatical literature, from Thai texts, and from informants.