The Collaborative International Dictionary of English v.0.48:

egg beater \egg beater\, egg-beater \egg-beater\n.
   a small device having one or usually two blades, each having
   several stiff oval wires at the tip. The blades are swirled
   or rotated for beating eggs or whipping cream. The electrical
   variety typically have two such blades, which are arranged so
   that the tips of the blades interlace while rotating.

   Syn: eggwhisk.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

eggbeater
    n 1: an aircraft without wings that obtains its lift from the
         rotation of overhead blades [syn: helicopter, chopper,
         whirlybird, eggbeater]
    2: a mixer for beating eggs or whipping cream [syn: eggbeater,
       eggwhisk]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "eggbeater":
   agitator, beater, blender, cement mixer, chopper, churn, copter,
   crucible, emulsifier, helicopter, jiggler, melting pot, mixer,
   paddle, rotary-wing aircraft, rotor plane, shaker, vibrator,
   whirlybird, whisk, windmill