Final answer:
The joint with no single unified capsule or common synovial cavity is a synovial joint, known for its joint cavity filled with synovial fluid that enables smooth and wide-ranging motion.
Step-by-step explanation:
The joint that resembles three separate joints with no single unified capsule or common synovial cavity is referred to as a synovial joint.
Synovial joints are characterized by the presence of a joint cavity, which is filled with synovial fluid, providing lubrication for the articulating bone surfaces within the joint. This fluid-filled space is where the articulating surfaces come into contact, allowing for smooth movement against each other, and it is enclosed by the articular capsule.
Unlike fibrous and cartilaginous joints, synovial joints don't have their bone surfaces directly connected by fibrous connective tissue or cartilage, which grants them greater freedom for movement.
As such, synovial joints are capable of a wide range of motions, making them the most mobile type of joint in the human body.