The Collaborative International Dictionary of English v.0.48:

Fuel \Fu"el\, n. [OF. fouail, fuail, or fouaille, fuaille, LL.
   focalium, focale, fr. L. focus hearth, fireplace, in LL.,
   fire. See Focus.] [Formerly written also fewel.]
   1. Any matter used to produce heat by burning; that which
      feeds fire; combustible matter used for fires, as wood,
      coal, peat, etc.
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   2. Anything that serves to feed or increase passion or
      excitement.
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   Artificial fuel, fuel consisting of small particles, as
      coal dust, sawdust, etc., consolidated into lumps or
      blocks.
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The Collaborative International Dictionary of English v.0.48:

Fuel \Fu"el\, v. t.
   1. To feed with fuel. [Obs.]
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            Never, alas I the dreadful name,
            That fuels the infernal flame.        --Cowley.
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   2. To store or furnish with fuel or firing. [Obs.]
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            Well watered and well fueled.         --Sir H.
                                                  Wotton.
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WordNet (r) 3.0 (2006):

fuel
    n 1: a substance that can be consumed to produce energy; "more
         fuel is needed during the winter months"; "they developed
         alternative fuels for aircraft"
    v 1: provide with a combustible substance that provides energy;
         "fuel aircraft, ships, and cars"
    2: provide with fuel; "Oil fires the furnace" [syn: fuel,
       fire]
    3: take in fuel, as of a ship; "The tanker fueled in Bahrain"
    4: stimulate; "fuel the debate on creationism"