folio

noun (plural folios)

• an individual leaf of paper or parchment, numbered on the recto or front side only, occurring either loose as one of a series or forming part of a bound volume.
• Printing the page number in a printed book.
• a sheet of paper folded once to form two leaves (four pages) of a book.
• a size of book made up of folio sheets of paper:copies in folio
• a book or manuscript made up of folio sheets of paper; a volume of the largest standard size:old vellum-bound folios [as modifier]:a folio volume