Source : Webster's Revised Unabridged Dictionary (1913)

Knee \Knee\, n. [OE. kne, cneo, As. cne['o], cne['o]w; akin to
   OS. knio, kneo, OFries. kn[=i], G. & D. knie, OHG. chniu,
   chneo, Icel. kn?, Sw. kn["a],Dan. kn[ae], Goth. kniu, L.
   genu, Gr. ?, Skr. j[=a]nu, ? Cf. {Genuflection}.]
   1. In man, the joint in the middle part of the leg.

   2. (Anat.)
      (a) The joint, or region of the joint, between the thigh
          and leg.
      (b) In the horse and allied animals, the carpal joint,
          corresponding to the wrist in man.

   3. (Mech. & Shipbuilding) A piece of timber or metal formed
      with an angle somewhat in the shape of the human knee when
      bent.

   4. A bending of the knee, as in respect or courtesy.

            Give them title, knee, and approbation. --Shak.

   {Knee breeches}. See under {Breeches}.

   {Knee holly}, {Knee holm} (Bot.), butcher's broom.

   {Knee jerk} (Physiol.) a jerk or kick produced by a blow or
      sudden strain upon the patellar tendon of the knee, which
      causes a sudden contraction of the quadriceps muscle; one
      of the so-called tendon reflexes.

   {Knee joint}. See in the Vocabulary.

   {Knee timber}, timber with knees or angles in it.

   {Knee tribute}, or {Knee worship}, tribute paid by kneeling;
      worship by genuflection. [Obs.] ``Knee tribute yet
      unpaid.'' --Milton.

Knee \Knee\ (n[=e]), v. t.
   To supplicate by kneeling. [Obs.]

         Fall down, and knee The way into his mercy. --Shak

Source : WordNet®

knee
     n 1: hinge joint in the human leg connecting the tibia and fibula
          with the femur and protected in front by the patella
          [syn: {knee joint}, {articulatio genus}, {genu}]
     2: joint between the femur and tibia in a quadruped;
        corresponds to the human knee [syn: {stifle}]
     3: cloth covering consisting of the part of a trouser leg that
        covers the knee