Gazetteers are more than basic place name directories containing names and locations for named geographic places. Most of them contain additional information, including a categorization of gazetteer entries using a typing scheme. This paper focuses on the nature of these categorization schemes. We argue that gazetteers can benefit from an ontological approach to typing schemes, providing a formalization that will better support gazetteer applications, maintenance, interoperability, and semi‐automatic feature annotation. We discuss the process of developing such an ontology as a modification of an existing feature type thesaurus; the difficulties in mapping from thesauri to ontologies are described in detail. To demonstrate the benefits of a categorization based on ontologies, a new gazetteer Web (and programming) interface is introduced and the impact on gazetteer interoperability is discussed.