[ kwawr-toh ]
/ ˈkwɔr toʊ /

noun, plural quar·tos.

a book size of about 9½ × 12 inches (24 × 30 cm), determined by folding printed sheets twice to form four leaves or eight pages. Symbol: 4to, 4°
a book of this size.


bound in quarto.

Origin of quarto

1580–90; short for New Latin in quartō in fourth (quartō, ablative singular of quartus fourth)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for quarto

British Dictionary definitions for quarto


/ (ˈkwɔːtəʊ) /

noun plural -tos

a book size resulting from folding a sheet of paper, usually crown or demy, into four leaves or eight pages, each one quarter the size of the sheetOften written: 4to,
(formerly) a size of cut paper 10 in. by 8 in. (25.4 cm by 20.3 cm)

Word Origin for quarto

C16: from New Latin phrase in quartō in quarter
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for quarto



"book from paper folded to make four pages to the sheet," late 15c., from Medieval Latin in quarto "in the fourth (part of a sheet of paper)," from quarto, ablative singular of Latin quartus "fourth" (see quart).

Online Etymology Dictionary, © 2010 Douglas Harper