This paper describes the development and use of a lexical semantic database for the Verbmobil speech-to-speech machine translation system. The motivation is to provide a common information source for the distributed development of the semantics, transfer and semantic evaluation modules and to store lexical semantic information application-independently. The database is organized around a set of abstract semantic classes and has been used to define the semantic contributions of the lemmata in the vocabulary of the system, to automatically create semantic lexica and to check the correctness of the semantic representations built up. The semantic classes are modelled using an inheritance hierarchy. The database is implemented using the lexicon formalism LeX4 developed during the project.