Final answer:
The weakest joint type is a fibrous joint, which is held together by fibrous connective tissue and lacks a joint cavity.
Step-by-step explanation:
In the classification of joints, the weakest joint type is the fibrous joint. Fibrous joints are held together by fibrous connective tissue and do not have a cavity between the bones, limiting their movement. Examples of fibrous joints include the joints in the skull and between teeth and sockets. In contrast, cartilaginous joints are connected by cartilage, and synovial joints have a space between the adjoining bones and allow for greater movement.