n. pl. oc·to·dec·i·mos 1. The page size, 4 by 6.5 inches, of a book composed of printer's sheets folded into 18 leaves or 36 pages. 2. A book composed of octodecimo pages. In both senses also called eighteenmo. [Late Latin (in) octōdecimō, (in) an eighteenth, ablative sing. of octōdecimus, eighteenth, from Latin octōdecim, eighteen : octō, eight; see oktō(u) in the Appendix of Indo-European roots + decem, ten; see dek in the Appendix of Indo-European roots.] |
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