The word 'prosthesis' carries within it one of the most productive roots in Indo-European linguistics — PIE *dʰeh₁- (to put, to set, to place), the ancestor of Greek 'tithenai,' Latin 'facere,' and English 'do.' A prosthesis is, at its etymological core, something placed in addition, something added to complete what is missing. The Greek compound 'prostithenai' (to put to, to add) joined 'pros' (toward, in addition to) with 'tithenai' (to place), and its noun 'prosthesis' originally named any kind of addition in a general sense.
The word's earliest English appearances were in rhetoric, not medicine. In Greek rhetorical theory, 'prosthesis' named the addition of a syllable or letter to the beginning of a word — a linguistic supplement, analogous to the physical one. This grammatical sense was borrowed into Latin and thence into early modern English. The medical sense — an artificial substitute for a missing body part — developed through the eighteenth and nineteenth centuries
The Greek 'tithenai' (τιθέναι, to place, to put) from *dʰeh₁- produced an extraordinary family of words in English, all built on the suffix '-thesis' (a placing). 'Thesis' (something placed, a proposition put forward) gives 'antithesis' (a placing against), 'synthesis' (a placing together), 'hypothesis' (a placing under, a foundational assumption), 'parenthesis' (a placing in beside, an insertion), 'epithet' (placed upon, a descriptive name), and 'theme' (from 'thema,' something placed, a topic). Every time one formulates a thesis, hypothesizes, or opens a parenthesis, one is using the same PIE root as the surgeon who fits a prosthetic limb.
In Latin, *dʰeh₁- became 'facere' (to make, to do), one of the most productive verbs in the language. English inherited from it: 'fact' (something made/done), 'factory,' 'manufacture,' 'satisfy,' 'affair,' 'feature,' 'fashion,' 'deficit,' 'perfect,' 'infect,' 'effect,' 'affect,' 'office,' 'sacrifice,' and hundreds more. In the Germanic branch, *dʰeh₁- produced Old English 'dōn' (to do), Modern English 'do' and 'deed.' The Sanskrit cognate
The history of physical prostheses is ancient. Archaeological evidence of prosthetic toes in ancient Egypt dates to around 950 BCE. Roman soldiers used iron hands. Renaissance craftsmen built articulated metal hands for injured knights — the most famous being the iron hand of Götz von Berlichingen (1480–1562), immortalized by Goethe. Modern prosthetics,
The word 'prosthetics' (the branch of medicine dealing with prostheses) and the adjective 'prosthetic' both derive from the same Greek root, extending the word family into the clinical vocabulary of rehabilitation medicine. In each case, the meaning is the same as it was in ancient Greek rhetoric: an addition, a supplement, something placed in to complete what was interrupted.