Quar"to (?), a. [L. in quarto in fourth, from quartus the fourth: cf. F. (in) quarto. See Quart.]
Having four leaves to the sheet; of the form or size of a quarto.
© Webster 1913.
Quar"to, n.; pl. Quartos ().
Originally, a book of the size of the fourth of sheet of printing paper; a size leaves; in present usage, a book of a square or nearly square form, and usually of large size.
© Webster 1913.