plaster cast

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A sculptured mold or cast in plaster of Paris.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun surgery A cast made of a stiff material (often plaster of Paris and gauze) in order to immobilize a broken bone for the period of healing.
• noun A copy of a piece of art or other object cast in plaster.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun bandage consisting of a firm covering (often made of plaster of Paris) that immobilizes broken bones while they heal