Source : Webster's Revised Unabridged Dictionary (1913)

Elbow \El"bow\, n. [AS. elboga, elnboga (akin to D. elleboga,
   OHG. elinbogo, G. ellbogen, ellenbogen, Icel. ?lnbogi; prop.;
   arm-bend); eln ell (orig., forearm) + boga a bending. See 1st
   {Ell}, and 4th {Bow}.]
   1. The joint or bend of the arm; the outer curve in the
      middle of the arm when bent.

            Her arms to the elbows naked.         --R. of
                                                  Gloucester.

   2. Any turn or bend like that of the elbow, in a wall,
      building, and the like; a sudden turn in a line of coast
      or course of a river; also, an angular or jointed part of
      any structure, as the raised arm of a chair or sofa, or a
      short pipe fitting, turning at an angle or bent.

   3. (Arch.) A sharp angle in any surface of wainscoting or
      other woodwork; the upright sides which flank any paneled
      work, as the sides of windows, where the jamb makes an
      elbow with the window back. --Gwilt.

   Note: Elbow is used adjectively or as part of a compound, to
         denote something shaped like, or acting like, an elbow;
         as, elbow joint; elbow tongs or elbow-tongs; elbowroom,
         elbow-room, or elbow room.

   {At the elbow}, very near; at hand.

   {Elbow grease}, energetic application of force in manual
      labor. [Low]

   {Elbow in the hawse} (Naut.), the twisting together of two
      cables by which a vessel rides at anchor, caused by
      swinging completely round once. --Totten.

   {Elbow scissors} (Surg.), scissors bent in the blade or shank
      for convenience in cutting. --Knight.

   {Out at elbow}, with coat worn through at the elbows; shabby;
      in needy circumstances.

Elbow \El"bow\, v. t. [imp. & p. p. {Elbowed}; p. pr. & vb. n.
   {Elbowing}.]
   To push or hit with the elbow, as when one pushes by another.

         They [the Dutch] would elbow our own aldermen off the
         Royal Exchange.                          --Macaulay.

   {To elbow one's way}, to force one's way by pushing with the
      elbows; as, to elbow one's way through a crowd.

Elbow \El"bow\, v. i.
   1. To jut into an angle; to project or to bend after the
      manner of an elbow.

   2. To push rudely along; to elbow one's way. ``Purseproud,
      elbowing Insolence.'' --Grainger.

Source : WordNet®

elbow
     n 1: hinge joint between the forearm and upper arm and the
          corresponding joint in the forelimb of a quadruped [syn:
           {elbow joint}, {cubitus}, {cubital joint}, {articulatio
          cubiti}]
     2: a sharp bend in a road or river
     3: a length of pipe with a sharp bend in it
     4: the part of a sleeve that covers the elbow; "his coat had
        patches over the elbows"
     5: the joint of a mammal or bird that corresponds to the human
        elbow

elbow
     v 1: push one's way with the elbows
     2: shove one's elbow into another person's ribs