Coxa and Hip joint

Coxa noun - The ball-and-socket joint between the head of the femur and the acetabulum.

Hip joint is a synonym for coxa. In some cases you can use "Hip joint" instead a noun "Coxa".

Hip joint noun - The ball-and-socket joint between the head of the femur and the acetabulum.

Coxa is a synonym for hip joint. You can use "Coxa" instead a noun phrase "Hip joint".