The Collaborative International Dictionary of English v.0.48:

Bobsled \Bob"sled`\, Bobsleigh \Bob"sleigh`\, n.
   1. A short sled, mostly used as one of a pair connected by a
      reach or coupling; also, the compound sled so formed. [U.
      S.]
      [1913 Webster]

            The long wagon body set on bobsleds.  --W. D.
                                                  Howells.
      [1913 Webster]

   2. a long racing sled (for 2 or more people), having two
      pairs of runners, with the front pair connected to a
      steering mechanism. They are usually raced one at a time
      down a steeply sloping path or specially constructed
      chute, with sharp banked curves, and attain high speeds.

   Syn: bobsled.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

bobsled
    n 1: formerly two short sleds coupled together [syn: bobsled,
         bobsleigh]
    2: a long racing sled (for 2 or more people) with a steering
       mechanism [syn: bobsled, bobsleigh, bob]
    v 1: ride a bobsled; "The boys bobbed down the hill screaming
         with pleasure" [syn: bobsled, bob]