The Collaborative International Dictionary of English v.0.48:

Radio- \Ra"di*o-\ (r[=a]"d[i^]*[-o]-), a.
   1. Of or pertaining to, or employing, or operated by, radiant
      energy, specifically that of electromagnetic waves with
      frequencies between those of infrared radiation and
      X-rays; hence, pertaining to, or employed in, broadcast
      radio or television, microwaves, radiotelephones, etc.;
      as, radio waves.
      [Webster 1913 Suppl. +PJC]

   2. of or pertaining to broadcast radio; as, a radio program.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Radio- \Ra"di*o-\ (r[=a]"d[i^]*[-o]-).
   A combining form indicating connection with, or relation to,
   a radius or ray; specifically (Anat.), with the radius of the
   forearm; as, radio-ulnar, radio-muscular, radio-carpal.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

electronic device \electronic device\ n.
   a device depending on the principles of electronics and using
   the manipulation of electron flow for its operation.
   [PJC]

   Note: Numerous electronic devices are in daily use, among
         them the television, radio, computer, robot,
         transmitter, receiver, VCR, CD player, etc.
         [PJC]

WordNet (r) 3.0 (2006):

radio
    adj 1: indicating radiation or radioactivity; "radiochemistry"
    n 1: medium for communication [syn: radio,
         radiocommunication, wireless]
    2: an electronic receiver that detects and demodulates and
       amplifies transmitted signals [syn: radio receiver,
       receiving set, radio set, radio, tuner, wireless]
    3: a communication system based on broadcasting electromagnetic
       waves [syn: radio, wireless]
    v 1: transmit messages via radio waves; "he radioed for help"