Folios

noun

1. A leaf of a book or manuscript
2. A page of a book, that is, one side of a leaf of a book.
3. A page number. The even folios are on the left-hand pages and the odd folios on the right-hand pages.
4. A sheet of paper folded in half.
5. (books) A book made of sheets of paper each folded in half (two leaves or four pages to the sheet); hence, a book of the largest kind, exceeding 30 cm in height.

   "A rare copy of Shakespeare’s First Folio."