Definition of: prosthesis

(pros′thə·sis) noun
1. The addition of a letter or syllable to a word, especially at the beginning, as yclept, bewail: also spelled prothesis.
2. Surg. The fitting of artificial parts to the body, as a glass eye, a false tooth, etc.
3. Replacement or substitution of parts. [<L <Gk., addition <prostithenai add <pros- toward, besides + tithenai place, put]
—pros·thet·ic (pros·thet′ik) adjective