Source : Webster's Revised Unabridged Dictionary (1913)

Nut \Nut\, n. [OE. nute, note, AS. hnutu; akin to D. noot, G.
   nuss, OHG. nuz, Icel. hnot, Sw. n["o]t, Dan. n["o]d.]
   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.

   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 lst {Bolt}.

   3. The tumbler of a gunlock. --Knight.

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

   {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} (Zo["o]l.), any leucosoid crab of the genus
      {Ebalia} as, {Ebalia tuberosa} of Europe.

   {Nut grass} (Bot.), a plant of the Sedge family ({Cyperus
      rotundus}, var. Hydra), which has slender rootstocks
      bearing small, nutlike tubers, by which the plant
      multiplies exceedingly, especially in cotton fields.

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

Source : WordNet®

nut grass
     n : a widely distributed perennial sedge having small edible
         nutlike tubers [syn: {nutgrass}, {nutsedge}, {nut sedge},
          {Cyperus rotundus}]