Environment can be defined as the natural world in which people, animals and plants live. It includes the biotic components like flora and fauna, the abiotic components such as air, water, soil and minerals, and the climatic conditions that affect the behaviour and development of all living beings on the earth. Today, the protection and improvement of environment is a major issue because various organic and non-organic pollutants like industrial and vehicular emissions, pesticides and by-products of factories are linked with a wide range of adverse impacts on human health, wildlife and vegetation. Realising the importance of environment, and considering the need to curb the unsustainable practices that are polluting the environment, several international organizations including the United Nations have emphasised to develop a common outlook and form common principles to address the problems relating to environment such as global warming, depletion of ozone layer and damaging of natural eco-systems, etc. Any action plan for the protection of environment necessitates the knowledge of various terms relating to environment and the exact connotations thereof. Moreover, environment is such a vast phenomenon that its different aspects cannot be fully understood until we have grasped its terminology. An explanation of terms like global warming tells us about the causes of an increase in earth’s mean temperature due to burning of greenhouse gases, as well as its grave consequences such as melting of glaciers, changes in climate patterns and intensification of hurricanes, floods and famines in different parts of the world. This Dictionary of Environment ably serves the twin purposes of providing valuable information about environment through a comprehensive terminology, and creating an awareness at the grassroots level by explaining the causes and consequences of various unsustainable human activities. The book will be highly useful for the students and teachers of Earth Science, Environment, Geography and Geology. The aspiring candidates of various competitive examinations will find it immensely helpful. It will greatly benefit the researchers and scholars in these fields. Common readers and those concerned with environment will find it highly informative.