The Collaborative International Dictionary of English v.0.48:

Scrambler \Scram"bler\, n.
   1. One who scrambles; one who climbs on all fours.
      [1913 Webster]

   2. A greedy and unceremonious contestant.
      [1913 Webster]

WordNet (r) 3.0 (2006):

scrambler
    n 1: a rapid mover; someone who scrambles; "their quarterback
         was a good scrambler"; "scramblers can often unnerve a
         better tennis player"
    2: a lightweight motorcycle equipped with rugged tires and
       suspension; an off-road motorcycle designed for riding cross
       country or over unpaved ground [syn: trail bike, dirt
       bike, scrambler]
    3: electronic equipment that makes speech unintelligible during
       transmission and restores it at reception