Source : Webster's Revised Unabridged Dictionary (1913)

Radiotelegraph \Ra`di*o*tel"e*graph\, n. [Radio- + telegraph.]
   A wireless telegraph.

Source : WordNet®

radiotelegraph
     n 1: telegraphy that uses transmission by radio rather than by
          wire [syn: {radiotelegraphy}, {wireless telegraphy}]
     2: the use of radio to send telegraphic messages (usually by
        Morse code) [syn: {radiotelegraphy}, {wireless telegraph},
         {wireless telegraphy}]