Which term refers to non-movable joints?

The term that refers to non-movable joints is synarthrosis. Synarthrosis describes a type of joint where there is little to no movement between the bones that articulate at the joint. This term is commonly used to categorize joints based on their mobility, with synarthrosis being one of three primary types, the others being amphiarthrosis (slightly movable) and diarthrosis (freely movable).

In the context of anatomy, examples of synarthrotic joints include sutures in the skull, which are tightly bound by connective tissue, preventing any motion. This immobility serves to provide stability and protect critical structures, such as the brain.

Other terms listed do not relate to non-movable joints specifically. For instance, synovial refers to freely movable joints that are characterized by a synovial cavity filled with synovial fluid. Supine is a body position lying face up, while supination describes a rotational movement of the forearm or foot that results in the palm facing up or forward and the foot arching upward. None of these terms pertain to non-movable joints in the anatomical sense.