prothesis
noun
proth·e·sis ˈprä-thə-səs 
plural protheses ˈprä-thə-ˌsēz
: the addition of a sound to the beginning of a word (as in Old French estat—whence English estate—from Latin status)
prothetic
prä-ˈthe-tik
adjective 
Word History
Etymology
Late Latin, alteration of prosthesis, from Greek, literally, addition — more at prosthesis
First Known Use
circa 1550, in the meaning defined above
Medical Definition
prothesis
noun
proth·e·sis ˈpräth-ə-səs
plural protheses -ˌsēz
: prosthesis