Scale \Scale\, n. [Cf. AS. scealu, scalu, a shell, parings;
         akin
   to D. schaal, G. schale, OHG. scala, Dan. & Sw.
         skal a shell,
   Dan. skiael a fish scale, Goth. skalja
         tile, and E. shale,
   shell, and perhaps also to scale of
         a balance; but perhaps
   rather fr. OF. escale, escaile,
         F. ['e]caille scale of a
   fish, and ['e]cale shell of
         beans, pease, eggs, nuts, of
   German origin, and akin to
         Goth. skalja, G. schale. See
   Shale.]
   1. (Anat.) One of
         the small, thin, membranous, bony or horny
      pieces
         which form the covering of many fishes and
      reptiles,
         and some mammals, belonging to the dermal part
      of the
         skeleton, or dermoskeleton. See Cycloid,
      Ctenoid,
         and Ganoid.
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         Webster]

            Fish that, with their fins and shining scales,
            Glide under the green wave.           --Milton.
     
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   2. Hence, any layer or leaf of metal or
         other material,
      resembling in size and thinness the
         scale of a fish; as, a
      scale of iron, of bone, etc.

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   3. (Zool.) One of the small
         scalelike structures covering
      parts of some
         invertebrates, as those on the wings of
      Lepidoptera
         and on the body of Thysanura; the elytra of
      certain
         annelids. See Lepidoptera.
     
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   4.
         (Zool.) A scale insect. (See below.)
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         Webster]

   5. (Bot.) A small appendage like a
         rudimentary leaf,
      resembling the scales of a fish in
         form, and often in
      arrangement; as, the scale of a
         bud, of a pine cone, and
      the like. The name is also
         given to the chaff on the stems
      of ferns.
     
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   6. The thin metallic side plate of the
         handle of a
      pocketknife. See Illust. of
         Pocketknife.
     
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   7. An
         incrustation deposit on the inside of a vessel in which
   
           water is heated, as a steam boiler.
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         Webster]

   8. (Metal.) The thin oxide which forms on the
         surface of iron
      forgings. It consists essentially of
         the magnetic oxide,
      Fe3O4. Also, a similar
         coating
         upon other metals.
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   {Covering
         scale} (Zool.), a hydrophyllium.

   Ganoid scale.
         (Zool.) See under Ganoid.

   Scale armor
         (Mil.),
         armor made of small metallic scales
      overlapping, and
         fastened upon leather or cloth.

   Scale beetle
         (Zool.), the tiger beetle.

   Scale carp (Zool.), a
         carp having normal scales.

   Scale insect (Zool.),
         any
         one of numerous species of small
      hemipterous insects
         belonging to the family Coccidae, in
      which
         the
         females, when adult, become more or less
      scalelike in
         form. They are found upon the leaves and
      twigs of
         various trees and shrubs, and often do great
      damage
         to fruit trees. See Orange scale,under Orange.
     
         

   Scale moss
         (Bot.), any leafy-stemmed moss of the
         order
      Hepaticae; -- so called
         from the small
         imbricated
      scalelike leaves of most of the species.
         See Hepatica,
      2,
         and Jungermannia.

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         Webster]