femur

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A bone of the leg situated between the pelvis and knee in humans. It is the largest and strongest bone in the body.
2. n. A functionally similar bone in the leg or hind limb of a vertebrate animal. Also called thighbone.
3. n. The thick, most muscular segment of the insect leg, situated between the trochanter and the tibia.

Century Dictionary and Cyclopedia

1. n. The thigh.
2. n. In anatomy, the thigh-bone; the single long bone which extends along the thigh from the hip-joint to the knee-joint, articulating above with the pelvis, and below with the tibia, or the tibia and fibula. The human femur is the longest and largest bone in the body, having a nearly straight subcylindric shaft with a rough ridge, the linea Aspera, along its posterior surface, bearing upon its upper extremity, by an oblique neck, a hemispherical head, and two trochanters, the greater and the lesser, and expanding below into two large condyles, the inner and the outer, both of which articulate with the tibia, but neither with the fibula. The slenderness of the bone is beyond an average for mammals, though in some it is still slenderer. Many femora, as of the horse, develop a third trochanter, and also may articulate with both bones of the leg. The reception of the head of the femur in the acetabulum is such that it articulates above with all three of the pelvic bones, the ilium, the ischium, and the pubis. In birds the greater trochanter abuts against the ilium, and thus enters into the formation of the hip-joint. See also cuts under digitigrade, Dromæus, and Ichthyosauria.
3. n. In entomology, the thigh; the third joint of the leg, between the trochanter and the shank or tibia. See cut under corbiculum.
4. n. In architecture, the interstitial member between two channels in the triglyph of the Doric order.

Wiktionary

1. n. anatomy A thighbone.
2. n. A segment of the leg of an insect or arachnid.

GNU Webster's 1913

1. n. The thigh bone; -- it is the longest and thickest bone of the human skeleton, which extends from the pelvis to the knee.
2. n. The proximal segment of the hind limb containing the thigh bone; the thigh. See coxa.

WordNet 3.0

1. n. the longest and thickest bone of the human skeleton; extends from the pelvis to the knee