Prosthesis/prosthetic
They are called prosthetics or supports.
If you are missing part of your tongue, it may affect speech, eating, and swallowing. It is important to work with a speech therapist and healthcare provider to develop strategies to improve these functions and adapt to the changes in your mouth.
If a specific part of the brain is missing, other parts of the brain may be able to compensate for the lost function to some extent. However, the brain's ability to perform certain functions may be impaired or altered depending on which part is missing.
neck
Moving of a body part toward the main axis of the body is called adduction. Moving away from the main axis of the body is called abduction.
Abduction
Prosthesis/prosthetic
Candy is missing her left leg below the knee.
Handicapped is the term used, if some part is missing. disease is substituted by illness.
brain
In the series kyle xy the part that is missing is his belly button
a starfish is missing a few body parts like fins and tails
Arms.
Knee cap
regeneration
Artificial limbs, prosthetic limbs or prostheses.
It's called a deformity which is a missing part of the body or an extra part