The Collaborative International Dictionary of English v.0.48:

Femur \Fe"mur\ (f[=e]"m[u^]r), n.; pl. Femora
   (f[e^]m"[-o]*r[.a]). [L. thigh.] (Anat.)
   (a) The thigh bone; -- it is the longest and thickest bone of
       the human skeleton, which extends from the pelvis to the
       knee.
   (b) The proximal segment of the hind limb containing the
       thigh bone; the thigh. See Coxa.
       [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

femur
    n 1: the longest and thickest bone of the human skeleton;
         extends from the pelvis to the knee [syn: femur,
         thighbone, femoris]