This concise dictionary of organisms and their ecology contains over 10,000 entries on ecosystems, habitats, communities, populations, species, trophic structures, productivity, energetics, dynamics, associations, behavior, reproduction, and physiology. The taxonomy of plants, animals, monerans, protistans and fungi down to ordinal level is introduced, based on a modern system of classification favored by many workers. The definitions give brief details of structure, biology, distribution, diversity, common names, and taxa of special interest. For the majority of flowering plants and invertebrate animals the classification goes down to family level. Fossil groups are covered in a much more selective manner with an emphasis on vernacular names. Definitions are always clear and concise and the text is complemented by some 700 illustrations mostly of living organisms, but some showing biogeographical areas and a range of collecting equipment. This new dictionary has been developed from the authors’ earlier work, Dictionary of Ecology, Evolution, and Systematics (Cambridge University Press, 1982), to produce a less specialized book covering a subject field that can best be summed up as traditional natural history.