The Collaborative International Dictionary of English v.0.48:

Powder \Pow"der\, n. [OE. poudre, pouldre, F. poudre, OF. also
   poldre, puldre, L. pulvis, pulveris: cf. pollen fine flour,
   mill dust, E. pollen. Cf. Polverine, Pulverize.]
   1. The fine particles to which any dry substance is reduced
      by pounding, grinding, or triturating, or into which it
      falls by decay; dust.
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            Grind their bones to powder small.    --Shak.
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   2. An explosive mixture used in gunnery, blasting, etc.;
      gunpowder. See Gunpowder.
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   Atlas powder, Baking powder, etc. See under Atlas,
      Baking, etc.

   Powder down (Zool.), the peculiar dust, or exfoliation, of
      powder-down feathers.

   Powder-down feather (Zool.), one of a peculiar kind of
      modified feathers which sometimes form patches on certain
      parts of some birds. They have a greasy texture and a
      scaly exfoliation.

   Powder-down patch (Zool.), a tuft or patch of powder-down
      feathers.

   Powder hose, a tube of strong linen, about an inch in
      diameter, filled with powder and used in firing mines.
      --Farrow.

   Powder hoy (Naut.), a vessel specially fitted to carry
      powder for the supply of war ships. They are usually
      painted red and carry a red flag.

   Powder magazine, or Powder room. See Magazine, 2.

   Powder mine, a mine exploded by gunpowder. See Mine.

   Powder monkey (Naut.), a boy formerly employed on war
      vessels to carry powder; a powder boy.

   Powder post. See Dry rot, under Dry.

   Powder puff. See Puff, n.
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The Collaborative International Dictionary of English v.0.48:

Powder \Pow"der\, v. t. [imp. & p. p. Powdered; p. pr. & vb.
   n. Powdering.] [F. poudrer.]
   1. To reduce to fine particles; to pound, grind, or rub into
      a powder; to comminute; to pulverize; to triturate.
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   2. To sprinkle with powder, or as with powder; to be
      sprinkle; as, to powder the hair.
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            A circling zone thou seest
            Powdered with stars.                  --Milton.
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   3. To sprinkle with salt; to corn, as meat. [Obs.]
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The Collaborative International Dictionary of English v.0.48:

Powder \Pow"der\, v. i.
   1. To be reduced to powder; to become like powder; as, some
      salts powder easily.
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   2. To use powder on the hair or skin; as, she paints and
      powders.
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WordNet (r) 3.0 (2006):

powder
    n 1: a solid substance in the form of tiny loose particles; a
         solid that has been pulverized [syn: powder,
         pulverization, pulverisation]
    2: a mixture of potassium nitrate, charcoal, and sulfur in a
       75:15:10 ratio which is used in gunnery, time fuses, and
       fireworks [syn: gunpowder, powder]
    3: any of various cosmetic or medical preparations dispensed in
       the form of a pulverized powder
    v 1: make into a powder by breaking up or cause to become dust;
         "pulverize the grains" [syn: powderize, powderise,
         powder, pulverize, pulverise]
    2: apply powder to; "She powdered her nose"; "The King wears a
       powdered wig"