This note describes a project concerned with the nature, construction and use of specialised machine dictionaries, concentrating on one particular type, the terminological thesaurus. The system described here is capable of dynamically producing outline definitions of terms and it is this feature which distinguishes it from other automated dictionaries. Methods of terminological research are combined with linguistic programming techniques to produce a tool not only for the terminologist, who may use it to compile, manipulate and generate systematically structured glossaries, but also for end-users such as technical translators, teachers of Languages for Special Purposes, technical subject librarians, indexers, technical writers, researchers, indeed all users of (multilingual)terminology.