This document presents detailed "definitions" of more than 150 key terms covering the lexicon currently being used in the field of adult learning in 20 European countries. The document begins with an introduction that discusses the glossary's theoretical and historical references and includes 14 references and a 16-item bibliography. The introduction is followed by the glossary entries, which were developed by 40 experts of different nationalities and typically include the following elements: the term in English and/or the language in which it originated; the country/countries where the term developed; detailed information about the term's origin, evolution, and current usage; and one or more references. The key terms belong to the following categories: (1) theories and general concepts; (2) strategies and policies (general concepts, legislation and measures); (3) system and sectors (the general system, services, school, culture, work, organizations and providers); (4) organizations and providers; (5) programs, activities, and methods; (6) the public; and (7) adult learning operators. The various entries concern a wide variety of forms of adult education, including community, continuing, nonformal, popular, reflexive, vocational, work-based, literacy, open, civic, professional, and corporate education, as well as lifelong learning, self-directed learning, study associations, workers' universities, apprenticeships, and adult education programs for specific ethnic groups and special populations. (MN)