Octavo
WordNet
noun
(1) The size of a book whose pages are made by folding a sheet of paper three times to form eight leaves
WiktionaryText
Noun
- A sheet of paper 7 to 10 inches high and 4.5 to 6 inches wide, the size varying with the large original sheet used to create it. Made by folding the original sheet three times to produce eight leaves.
- A book of octavo pages.