General:
* Support: This is a broad term, but it can encompass the function of a brace or splint.
* Immobilizer: This emphasizes the function of keeping a body part still.
* Stabilizer: Similar to immobilizer, this emphasizes the function of providing stability.
Specific to type of support:
* Orthosis: This is a more formal term used to describe a device that supports a joint or limb.
* Cast: This is typically used for immobilizing a fractured bone.
* Sling: This is used to support an arm or shoulder.
* Collar: This is used to support the neck.
Informal:
* Bandage: This is a more general term for a piece of material used to support an injury.
* Support: This is a general term used for anything that helps hold up or stabilize something.
The best word to use will depend on the specific situation and the desired level of formality.