The Collaborative International Dictionary of English v.0.48:

Spark \Spark\, n. [OE. sparke, AS. spearca; akin to D. spark,
   sperk; cf. Icel. spraka to crackle, Lith. sprag["e]ti, Gr. ?
   a bursting with a noise, Skr. sph?rj to crackle, to thunder.
   Cf. Speak.]
   1. A small particle of fire or ignited substance which is
      emitted by a body in combustion.
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            Man is born unto trouble, as the sparks fly upward.
                                                  --Job v. 7.
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   2. A small, shining body, or transient light; a sparkle.
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   3. That which, like a spark, may be kindled into a flame, or
      into action; a feeble germ; an elementary principle. "If
      any spark of life be yet remaining." --Shak. "Small
      intellectual spark." --Macaulay. "Vital spark of heavenly
      flame." --Pope.
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            We have here and there a little clear light, some
            sparks of bright knowledge.           --Locke.
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            Bright gem instinct with music, vocal spark.
                                                  --Wordsworth.
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   Spark arrester, a contrivance to prevent the escape of
      sparks while it allows the passage of gas, -- chiefly used
      in the smokestack of a wood-burning locomotive. Called
      also spark consumer. [U.S.]
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WordNet (r) 3.0 (2006):

spark arrester
    n 1: electrical device to reduce sparking when electrical
         contacts are opened or closed
    2: a wire net to stop sparks from an open fireplace or
       smokestack [syn: spark arrester, sparker]