Final answer:
Crepitation is the medical term for a grating sound made by the movement of some joints or broken bones, often associated with conditions like arthritis.
Step-by-step explanation:
The grating sound made by the movement of some joints or broken bones is called crepitation. This occurs when the articular surfaces of bones in a joint rub against each other, which can happen when cartilage is worn down or when bone fragments are present. It is also a common sign in conditions such as arthritis, where joint surfaces become rough, leading to this noise during movement.