Thoroughly revised and updated this Third Edition reflects the great diversity of disciplines that have an impact on this field of study. The more than 5,400 extensively cross-referenced entries - including approximately 450 new to this edition - are drawn from agriculture, biology, chemistry, engineering, medicine, microbiology, soil science, geology, meteorology, toxicology, government, law, and more. This updated volume also contains revised backmatter, including Web resources, as well as new line illustrations.