tome (n.) Look up tome at Dictionary.com
1510s, "a single volume of a multi-volume work," from Middle French tome (16c.), from Latin tomus "section of a book, tome," from Greek tomos "volume, section of a book," originally "a section, piece cut off," from temnein "to cut," from PIE *tem- "to cut" (cognates: second element in Latin aestimare "to value, appraise," Old Church Slavonic tina "to cleave, split," Middle Irish tamnaim "I cut off," Welsh tam "morsel"). Sense of "a large book" is attested from 1570s.