The femur is the thigh bone. In humans, it is the longest, most voluminous, and strongest bone. The average human femur is 48 centimeters (19 in) in length and 2.34 cm (0.92 in) in diameter and can support up to 30 times the weight of an adult. It forms part of the hip (at the acetabulum) and part of the knee.
The word femur is Latin for thigh. Theoretically in strict usage, femur bone is more proper than femur, as in classical Latin femur means "thigh", and os femoris means "the bone within it".
In medical Latin its genitive is always femoris, but in classical Latin its genitive is often feminis, and should not be confused with case forms of femina, which means "woman".
The intercondylar fossa is present between the condyles at the distal
end of the femur. In addition to the intercondylar eminence on the tibial plateau, there is both an anterior and posterior intercondylar fossa (area), the sites of anterior cruciate and posterior cruciate ligament attachment, respectively.
In other animals
Parallel structures by the same name exist in other complex animals, such as the bone inside a ham
or a leg of lamb
. The name femur is also given to the most proximal
full-length jointed segment of an arthropod