Characterized in this article is a reverse dictionary of contempory official names of localities in Poland that has been prepared for publication. It is based on 55 thousand different names for approximately one hundred thousand inhabited places. There are several times that many entries in the dictionary because all the component elements of compound toponyms are presented. This creates an enormous collection that combines a reverse dictionary with a derivational-semantic lexicon. For that reason, it can be used to analyze the construction and meaning of oikonoyms, and to designate frequency and areas of individual onymic types. The dictionary also makes possible comparison of terrain names and appellatives.