A device that replaces a missing body part is called a prosthetic.
Prosthetics are artificial devices designed to replace a missing part of the body, such as a limb, tooth, eye, or other body part. Some common examples include:

• Prosthetic limbs (arms, legs, hands, feet) for people who have lost a limb
• Prosthetic eyes for those who have lost an eye
• Prosthetic breasts after a mastectomy
• Dental prosthetics like dentures, bridges, or implants to replace missing teeth
• Auditory prosthetics like hearing aids or cochlear implants for hearing loss

Prosthetics are designed to restore function, appearance, or both for the missing body part. They can be custom-fitted and made from various materials like plastics, metals, or composites depending on the application.