Is it ensure, insure, or assure?
1510s, from Middle French tome, from Latin tomus "section of a book, tome," from Greek tomos "volume, section of a book," originally "section, piece cut off," from temnein "to cut," from PIE *tom-/*tem- "to cut" (cf. second element in Latin aestimare "to value, appraise," Old Church Slavonic tina "to cleave, split," Middle Irish tamnaim "I cut off," Welsh tam "morsel"). Originally "a single volume of a multi-volume work;" sense of "a large book" is attested from 1570s.
Part; area; segment: dermatome.
Cutting instrument: microtome.