The publication of a second edition of the INTERNATIONAL DICTIONARY OF PHYSICS AND ELECTRONICS within less than five years of the publication of the first edition has been made desirable by the rapid progress in some of the fields of physics and electronics. The breakdown of parity conservation, the growth of hydromagnetics and other forms of fluid mechanics, the completion of more powerful accelerators, the rapid application of transistors and the increased quality and quantity of computers are examples of the many changes that result in the introduction of new terms and modifications in the meaning of old ones.Another new feature of the Second Edition is the group of multilingual indices, in French, German, Spanish and Russian. They have been added to meet the ever-growing use and importance of the foreign literature.