Entry 2 senses Webster, 1913 Fathomless · Fath·om·less · IPA /ˈfæ.ðəm.ləs/ 01 a. Incapable of being fathomed; immeasurable; that can not be sounded. 1. Incapable of being fathomed; immeasurable; that can not be sounded. “And buckle in a waist most fathomless.” — Shak. 2. Incomprehensible. “The fathomless absurdity.” — Milton.