Mapping and assessment of ecosystems and their services (MAES) is a key EU initiative to synthesise vital environmental information and facilitate balanced policy decisions. As MAES integrates across many scientific and policy domains, the development of a common language and shared concepts is essential. Here we present a comprehensive MAES Glossary that was compiled in the ESMERALDA project; it is based on the integration of several previous glossaries and a wide-ranging consultation process. While there are several ecosystem services glossaries available from EU supported work such as Oppla, OpenNESS and ecosystem services related handbooks, the new material presented here focuses on mapping and assessment of ecosystem services and therefore more directly supports the MAES process.