The Collaborative International Dictionary of English v.0.48:

defroster \defroster\ n.
   A device that removes ice or frost (as from a windshield or a
   refrigerator or the wings of an airplane).

   Syn: deicer.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

defroster
    n 1: heater that removes ice or frost (as from a windshield or a
         refrigerator or the wings of an airplane) [syn:
         defroster, deicer]