The Collaborative International Dictionary of English v.0.48:

Bank \Bank\ (b[a^][ng]k), n. [OE. banke; akin to E. bench, and
   prob. of Scand. origin; cf. Icel. bakki. See Bench.]
   1. A mound, pile, or ridge of earth, raised above the
      surrounding level; hence, anything shaped like a mound or
      ridge of earth; as, a bank of clouds; a bank of snow.
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            They cast up a bank against the city. --2 Sam. xx.
                                                  15.
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   2. A steep acclivity, as the slope of a hill, or the side of
      a ravine.
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   3. The margin of a watercourse; the rising ground bordering a
      lake, river, or sea, or forming the edge of a cutting, or
      other hollow.
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            Tiber trembled underneath her banks.  --Shak.
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   4. An elevation, or rising ground, under the sea; a shoal,
      shelf, or shallow; as, the banks of Newfoundland.
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   5. (Mining)
      (a) The face of the coal at which miners are working.
      (b) A deposit of ore or coal, worked by excavations above
          water level.
      (c) The ground at the top of a shaft; as, ores are brought
          to bank.
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   6. (A["e]ronautics) The lateral inclination of an
      a["e]roplane as it rounds a curve; as, a bank of 45[deg]
      is easy; a bank of 90[deg] is dangerous.
      [Webster 1913 Suppl.]

   7. A group or series of objects arranged near together; as, a
      bank of electric lamps, etc.
      [Webster 1913 Suppl.]

   8. The tilt of a roadway or railroad, at a curve in the road,
      designed to counteract centrifugal forces acting on
      vehicles moving rapiudly around the curve, thus reducing
      the danger of overturning during a turn.
      [PJC]

   Bank beaver (Zool.), the otter. [Local, U.S.]

   Bank swallow, a small American and European swallow
      (Clivicola riparia) that nests in a hole which it
      excavates in a bank.
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The Collaborative International Dictionary of English v.0.48:

Beaver \Bea"ver\, n. [OE. bever, AS. beofer, befer; akin to D.
   bever, OHG. bibar, G. biber, Sw. b[aum]fver, Dan. b[ae]ver,
   Lith. bebru, Russ. bobr', Gael. beabhar, Corn. befer, L.
   fiber, and Skr. babhrus large ichneumon; also as an adj.,
   brown, the animal being probably named from its color.
   [root]253. See Brown.]
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   1. (Zool.) An amphibious rodent, of the genus Castor.
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   Note: It has palmated hind feet, and a broad, flat tail. It
         is remarkable for its ingenuity in constructing its
         lodges or "houses," and dams across streams. It is
         valued for its fur, and for the material called
         castor, obtained from two small bags in the groin of
         the animal. The European species is Castor fiber, and
         the American is generally considered a variety of this,
         although sometimes called Castor Canadensis.
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   2. The fur of the beaver.
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   3. A hat, formerly made of the fur of the beaver, but now
      usually of silk.
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            A brown beaver slouched over his eyes. --Prescott.
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   4. Beaver cloth, a heavy felted woolen cloth, used chiefly
      for making overcoats.
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   5. A man's beard.
      [PJC]

   6. The hair on a woman's pubic area; -- vulgar. [vulgar
      slang]
      [PJC]

   7. A woman; -- vulgar and offensive. [vulgar slang]
      [PJC]

   8. A person who works enthusiastically and diligently; --
      used especially in the phrase eager beaver. [informal]
      [PJC]

   Beaver rat (Zool.), an aquatic ratlike quadruped of
      Tasmania (Hydromys chrysogaster).

   Beaver skin, the furry skin of the beaver.

   Bank beaver. See under 1st Bank.
      [1913 Webster]