define knee
A woman massages her knee. The definition of knee is the joint between the thigh and lower leg. An example of a knee is the part of the body on which a person kneels. Knee is defined as to hit or strike using the joint between the thigh and lower leg. An example of knee is to hit a soccer ball with this joint.
The knee joint joins the thigh with the leg and consists of two articulations: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee joint is vulnerable to injury and to the development of osteoarthritis. It is often termed a compound joint having tibiofemoral and patellofemoral components.