- (n.) A book composed of sheets each of which is folded into eighteen leaves; hence; indicating more or less definitely a size of book, whose sheets are so folded; -- usually written 18mo or 18ยก, and called eighteenmo.
- (a.) Having eighteen leaves to a sheet; as, an octodecimo form, book, leaf, size, etc.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). octodecimo. Retrieved September 20, 2026, from http://smartdefine.org/octodecimo/definitions/2038300 |
| Chicago | Webster's. 2011. "octodecimo" http://smartdefine.org/octodecimo/definitions/2038300 (accessed September 20, 2026). |
| Harvard | Webster's 2011, octodecimo, Smart Define, viewed 20 September, 2026, <http://smartdefine.org/octodecimo/definitions/2038300>. |
| MLA | Webster's. "octodecimo" 27 May 2011. Web. 20 September 2026. <http://smartdefine.org/octodecimo/definitions/2038300> |