In this paper we present a model and a corresponding ontology for associating lexical information to entities of a given domain ontology. In particular, we focus on representing subcategorization frames as well as their mapping to ontological structures. The lexicon model and ontology can thus be used to specify the syntax-semantic interface for ontology-based NLP systems which are expected to produce output compliant with a specific domain ontology. Our lexicon ontology itself is formalized in the OWL language, thus allowing the lexica to be published together with the domain ontologies. We also discuss different ways how the creation of appropriate lexica can be supported.