The Collaborative International Dictionary of English v.0.48:

Carburetor \Car"bu*ret`or\, Carburettor \Car"bu*ret`tor\, n.
   1. (Chem.) An apparatus in which coal gas, hydrogen, or air
      is passed through or over a volatile hydrocarbon, in order
      to confer or increase illuminating power. [Written also
      carburettor.]
      [1913 Webster]

   2. One that carburets; specif., an apparatus in which air or
      gas is carbureted, as by passing it through a light
      petroleum oil. The carburetor for a gasoline engine is
      usually either a surface carburetor, or alternatively a
      float carburetor (called also float-feed carburetor,
      or spray carburetor). In the former air is charged by
      being passed over the surface of gasoline. In the latter a
      fine spray of gasoline is drawn from an atomizing nozzle
      by a current of air induced by the suction of the engine
      piston, the supply of gasoline being regulated by a float
      which actuates a needle valve controlling the outlet of
      the feed pipe. Alcohol and other volatile inflammable
      liquids may be used instead of gasoline.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

carburetor
    n 1: mixes air with gasoline vapor prior to explosion [syn:
         carburetor, carburettor]