Source : Webster's Revised Unabridged Dictionary (1913)

Femur \Fe"mur\, n.; pl. {Femora}. [L. thigh.] (Anat.)
   (a) The thigh bone.
   (b) The proximal segment of the hind limb containing the
       thigh bone; the thigh. See {Coxa}.

Source : WordNet®

femur
     n : the longest and thickest bone of the human skeleton; extends
         from the pelvis to the knee [syn: {thighbone}, {femoris}]
     [also: {femora} (pl)]