The term REPLACEMENT PART can be defined as two crossword solutions: PROSTHESIS (10 letters) and HIP (3 letters). A prosthesis is an artificial device that replaces a missing body part, such as a limb or organ. It is typically made of materials such as metal, plastic, or ceramic. A HIP prosthesis is a type of prosthesis specifically designed to replace the HIP joint. It is usually made of metal and plastic components and is surgically implanted into the patient's HIP joint.