Femur n. : The thigh bone.

Femur n. : The proximal segment of the hind limb containing the thigh bone; the thigh. See Coxa.

Example:
How long should a Femur be in relation to your full height?

Taxonomy
femur, bone, femur bone, knee-joint, neck of the femur, human femur, body, vertebrates, legs, free encyclopedia, condyles, primitive, acetabulum, intercondylar fossa, thigh bone, land mammals, adult, protuberances.

Defination from the web:
femurs. One of the earliest known vertebrates to have a femur is the Eusthenopteron, a prehistoric lobe-finned fish from the Late Devonian period. ...