radio

\ \ [20] Radio began life, in the first decade of the 20th century, as an abbreviation of radiotelegraphy, a compound based on Latin radius. This originally meant ‘staff, stake’, but it is its secondary meanings that have contributed significantly to English: ‘spoke of a wheel’, for instance, lies behind English radius [16], and the notion of a ‘ray’ has produced radiant [15], radiate [17], radium [19] (etymologically a metal emitting ‘rays’), and indeed ray. Radiotelegraphy itself denoted the sending of messages by electromagnetic ‘rays’. Radar [20], coined in the USA in 1941, is an acronym formed from radio detection and ranging.

\ \ Cf.⇒ RADAR, RADIATE, RADIUS, RADIUM, RAY