The Collaborative International Dictionary of English v.0.48:

Firing \Fir"ing\, n.
   1. The act of discharging firearms.
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   2. The mode of introducing fuel into the furnace and working
      it. --Knight.
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   3. The application of fire, or of a cautery. --Dunglison.
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   4. The process of partly vitrifying pottery by exposing it to
      intense heat in a kiln.
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   5. Fuel; firewood or coal. [Obs.] --Mortimer.
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   Firing iron, an instrument used in cauterizing.
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