Pros"the*sis (?), n. [L., fr. Gr. an addition, fr. to put to, to add; to + to put, place.]
1. Surg.
The addition to the human body of some artificial part, to replace one that is wanting, as a log or an eye; -- called also prothesis.
2. Gram.
The prefixing of one or more letters to the beginning of a word, as in beloved.
© Webster 1913.