English▸ noun
(plural quartos)
[mass noun] Printing a size of book page resulting from folding each printed sheet into four leaves (eight pages). ▪ [count noun] a book of quarto size.
▪ a size of writing paper, 10 in. × 8 in. (254 × 203 mm).
– ORIGIN late 16th century: from Latin ( in) quarto ‘(in) the fourth (of a sheet)’, ablative of quartus ‘fourth’.