Joints that hold bones firmly together are called?

Synarthrosis joints are joints that hold bones firmly together so that no movement is permitted at the joint. The gomphoses that connect the teeth to the skull, and the sutures of the cranium, are each examples of synarthrosis joints.

Anatomists classify joints both structurally, based on the type of material present at the joint, and functionally based on the movement the joint allows between the bones. The movement-based joint classifications include synarthrosis, amphiarthrosis, and diarthrosis joints. The material based joints include fibrous joints, cartilaginous joints and the synovial joints. The synovial joints are the most commonly found in the human body