This accessible reference covers commonly encountered terms and concepts in physics and includes key terms from mathematics, astrophysics, metallurgy, electronics, and physical chemistry. The entries are written in a clear and explanatory style to provide both straightforward definitions and invaluable background information. This approach, combined with an extensive cross-referencing system, enables the reader to place each entry in a broader scientific context. Line drawings are included whenever the meaning of a word can best be conveyed by means of diagram, and a range of tables of essential scientific information is provided.