Final answer:
The socket for the head of the femur is called the acetabulum. It forms the hip joint with the head of the femur, creating a ball-and-socket joint allowing for extensive range of motion.
Step-by-step explanation:
The concave indentation that serves as the socket for the head of the femur is called the acetabulum. This deep, cup-shaped cavity is where the ilium, pubis, and ischium, the three areas of each hip bone, converge. It is part of the hip joint, central to providing stability and weight-bearing ability.
The head of the femur, with its fovea capitis for ligament attachment, articulates with the acetabulum to form the hip joint. The hip joint is a ball-and-socket joint, which is multiaxial and allows for a range of motion that includes anterior-posterior and medial-lateral directions, as well as rotation around the long axis of the femur.