The Collaborative International Dictionary of English v.0.48:

Cinder \Cin"der\ (s[i^]n"d[~e]r), n. [AS. sinder slag, dross;
   akin to Icel. sindr dross, Sw. sinder, G. sinter, D. sintel;
   perh. influenced by F. cendre ashes, fr. L. cinis. Cf.
   Sinter.]
   1. Partly burned or vitrified coal, or other combustible, in
      which fire is extinct.
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   2. A hot coal without flame; an ember. --Swift.
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   3. A scale thrown off in forging metal.
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   4. The slag of a furnace, or scoriaceous lava from a volcano.
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   Cinder frame, a framework of wire in front of the tubes of
      a locomotive, to arrest the escape of cinders.

   Cinder notch (Metal.), the opening in a blast furnace,
      through which melted cinder flows out.
      [1913 Webster]