All terms defined and explained in the glossary are included in an alphabetical list. An index helps to find a particular term easily and gives an overview of the terms included. Very often descriptive text, related terms, synonyms and antonyms are given in addition to the proper definition to help the reader to understand the term in its context and practical use. Sources have been specified for all the definitions or different parts of a definition and the descriptive text. The definition given is the one preferred and commonly used by FAO. Whenever useful or necessary, a general or basic definition has been added to a term which is defined for the purpose of integrated resource planning and management or related subjects. Where no agreement has been yet reached or definitions vary significantly from each other, more than one definition has been listed.