The Collaborative International Dictionary of English v.0.48:

Nut \Nut\ (n[u^]t), n. [OE. nute, note, AS. hnutu; akin to D.
   noot, G. nuss, OHG. nuz, Icel. hnot, Sw. n["o]t, Dan.
   n["o]d.]
   [1913 Webster]
   1. (Bot.) The fruit of certain trees and shrubs (as of the
      almond, walnut, hickory, beech, filbert, etc.), consisting
      of a hard and indehiscent shell inclosing a kernel.
      [1913 Webster]

   2. A perforated block (usually a small piece of metal),
      provided with an internal or female screw thread, used on
      a bolt, or screw, for tightening or holding something, or
      for transmitting motion. See Illust. of 1st Bolt.
      [1913 Webster]

   3. The tumbler of a gunlock. --Knight.
      [1913 Webster]

   4. (Naut.) A projection on each side of the shank of an
      anchor, to secure the stock in place.
      [1913 Webster]

   5. pl. Testicles. [vulgar slang]
      [PJC]

   Check nut, Jam nut, Lock nut, a nut which is screwed up
      tightly against another nut on the same bolt or screw, in
      order to prevent accidental unscrewing of the first nut.


   Nut buoy. See under Buoy.

   Nut coal, screened coal of a size smaller than stove coal
      and larger than pea coal; -- called also chestnut coal.


   Nut crab (Zool.), any leucosoid crab of the genus Ebalia
      as, Ebalia tuberosa of Europe.

   Nut grass (Bot.), See nut grass in the vocabulary.

   Nut lock, a device, as a metal plate bent up at the
      corners, to prevent a nut from becoming unscrewed, as by
      jarring.

   Nut pine. (Bot.) See under Pine.

   Nut rush (Bot.), a genus of cyperaceous plants (Scleria)
      having a hard bony achene. Several species are found in
      the United States and many more in tropical regions.

   Nut tree, a tree that bears nuts.

   Nut weevil (Zool.), any species of weevils of the genus
      Balaninus and other allied genera, which in the larval
      state live in nuts.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Buoy \Buoy\ (bwoi or boi; 277), n. [D. boei buoy, fetter, fr.
   OF. boie, buie, chain, fetter, F. bou['e]e a buoy, from L.
   boia. "Boiae genus vinculorum tam ferreae quam ligneae."
   --Festus. So called because chained to its place.] (Naut.)
   A float; esp. a floating object moored to the bottom, to mark
   a channel or to point out the position of something beneath
   the water, as an anchor, shoal, rock, etc.
   [1913 Webster]

   Anchor buoy, a buoy attached to, or marking the position
      of, an anchor.

   Bell buoy, a large buoy on which a bell is mounted, to be
      rung by the motion of the waves.

   Breeches buoy. See under Breeches.

   Cable buoy, an empty cask employed to buoy up the cable in
      rocky anchorage.

   Can buoy, a hollow buoy made of sheet or boiler iron,
      usually conical or pear-shaped.

   Life buoy, a float intended to support persons who have
      fallen into the water, until a boat can be dispatched to
      save them.

   Nut buoy or Nun buoy, a buoy large in the middle, and
      tapering nearly to a point at each end.

   To stream the buoy, to let the anchor buoy fall by the
      ship's side into the water, before letting go the anchor.


   Whistling buoy, a buoy fitted with a whistle that is blown
      by the action of the waves.
      [1913 Webster]