quarto

[ 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.

adjective

bound in quarto.

Origin of quarto

1580–90; short for New Latin in quartō in fourth (quartō, ablative singular of quartus fourth)
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Examples from the Web for quarto

British Dictionary definitions for quarto

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