Octavo has 2 different meanings across 1 category:
Noun
the size of a book whose pages are made by folding a sheet of paper three times to form eight leaves
A sheet of paper 7 to 10 inches (= 17.78 to 25.4 cm) high and 4.5 to 6 inches (= 11.43 to 15.24 cm) wide, the size varying with the large original sheet used to create it. It is made by folding the original sheet three times to produce eight leaves.