This ETSI Technical Report (ETR) is a collection of terms, definitions and abbreviations related to the baseline documents defining Universal Mobile Telecommunications System (UMTS) objectives and systems framework. This ETR provides a tool for further work on UMTS technical documentation and facilitates their understanding. The terms, definitions and abbreviations as given in this ETR are either imported from existing documentation (ETSI, ITU or elsewhere) or newly created by UMTS experts whenever the need for precise vocabulary was identified. New terms, definitions and abbreviations may emerge in new documents specifying UMTS in greater detail. In this process, the consistency of UMTS terminology is maintained with updates of this ETR. All efforts have been made to harmonize this vocabulary, i.e. to avoid conflicts with the usage of the same or similar terms in other not UMTS related applications.