Pow·der n.
 1. The fine particles to which any dry substance is reduced by pounding, grinding, or triturating, or into which it falls by decay; dust.
    Grind their bones to powder small.   --Shak.
 2. An explosive mixture used in gunnery, blasting, etc.; gunpowder. See Gunpowder.
 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.