This dictionary presents definitions of both the well-established terms and many new ones that have come into use with the advances that have taken place in the fields of radio and television. In many cases extended definitions are given in order to describe briefly elementary principles and circuits, while newer and more complex devices and systems are described in even greater detail where necessary to make clear the underlying principles or modes of operation. S ubjects extensively covered include: radiotelephones and radiotelegraphy; monochrome and color television; facsimile transmission; radio direction finding; receivers and transmitters; transistors; semiconductor and thermionic devices; audio and high fidelity reproduction; aerials, transmission lines, and waveguides; microwave techniques and tubes; communication satellites; propagation; television cameras; measuring instruments; and general electrical and radio terms. Also included are basic terms in the fields of radar, radio navigation, radio astronomy, studio equipment, and lasers. To supplement the definitions, a list of technical abbreviations is appended together with several useful tables. (JY)