quarto

This term is primarily used in bibliography and the study of rare books. It describes a specific physical format where a sheet of paper is folded twice, creating four leaves (eight pages). In a modern context, it is most frequently encountered when discussing early printed editions of literature, particularly the First Folio and various early versions of Shakespeare's plays.

When used as a noun to describe a specific book, it functions as a countable noun. However, when referring to the general format or size of the page, it often functions as an uncountable descriptor of a printing standard.