Source : Webster's Revised Unabridged Dictionary (1913)

Radiotelegraphy \Ra`di*o*te*leg"ra*phy\, n. [Radio- +
   telegraphy.]
   Telegraphy using the radiant energy of electrical (Hertzian)
   waves; wireless telegraphy; -- the term adopted for use by
   the Radiotelegraphic Convention of 1912.

Source : WordNet®

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