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.
 At·las pow·der. A blasting powder or dynamite composed of nitroglycerin, wood fiber, sodium nitrate, and magnesium carbonate.
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 At·las n.; pl. Atlases
 1. One who sustains a great burden.
 2. Anat. The first vertebra of the neck, articulating immediately with the skull, thus sustaining the globe of the head, whence the name.
 3. A collection of maps in a volume; --
 Note: supposed to be so called from a picture of Atlas supporting the world, prefixed to some collections. This name is said to have been first used by Mercator, the celebrated geographer, in the 16th century.
 4. A volume of plates illustrating any subject.
 5. A work in which subjects are exhibited in a tabular from or arrangement; as, an historical atlas.
 6. A large, square folio, resembling a volume of maps; -- called also atlas folio.
 7. A drawing paper of large size. See under Paper, n.
 Atlas powder, see Atlas powder in the vocabulary; a blasting compound containing nitroglycerin.