Entry 1 sense Webster, 1913 Prosthetic /präs-thĕt'-ĭk/ · Pros·thet·ic · IPA /ˌpɹɑsˈθɛtɪk/ 01 a. Of or pertaining to prosthesis; prefixed, as a letter or letters to a word. 1. Of or pertaining to prosthesis; prefixed, as a letter or letters to a word.