We see application of science everywhere. Whether we are aware or not, science application plays a big part in our daily lives. While you are reading this page, an important element of optical science is in use. Electricity, for example, is one of the most important science discoveries ever made. As we walk in the public, we see almost everyone carrying a cellular phone. This is an application of electronics & communications technology. To remain healthy, we use medicines, which is a specialised form of biology. It is only the knowledge of science which enables us to understand the life processes around us. V&S Publishers has brought for you dictionaries of terms in science, physics, chemistry and biology to make science simpler for you. The terms have been arranged alphabetically for quick reference. Suitable explanations of terms that have come into public domain recently also find mention. The standard of explanation has been kept at a level of understanding expected from an average secondary and senior secondary student. Illustrations and examples, at appropriate places, have been given. Readers who have not made a special study of any science subject will have also be able to grasp the definitions. Important scientific charts, tables, constants, conversion tables, etc., have been included as appendices to make this dictionary more useful. A glossary of Nobel Prize winners and their contributions is an added attraction.