The Collaborative International Dictionary of English v.0.48:

Radiotelegraphy \Ra`di*o*te*leg"ra*phy\
   (r[=a]`d[i^]*[o^]*t[e^]*l[e^]g"r[.a]*f[y^]), n. [Radio- +
   telegraphy.]
   Telegraphy using the radiant energy of radio waves; wireless
   telegraphy; -- the term adopted for use by the
   Radiotelegraphic Convention of 1912.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

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