1. An artificial device used to replace a missing body part, such as a limb, tooth, eye, or heart valve.
2. Replacement of a missing body part with such a device.
3. Linguistics. Prothesis.

[Greek, addition, from prostithenai, prosthe-, to add : pros-, pros- + tithenai, to put.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.