Folio (noun)

1. A sheet of paper folded in half to make two leaves, or four pages of a book or manuscript.
2. A book or manuscript consisting of sheets of paper folded in this way.
3. A number of sheets of paper or parchment bound together, constituting one section of a book or manuscript.

Origin:

Early 16th century: from latin folium "leaf".

Examples:

1. The manuscript was bound in folios.
2. The artist's sketches were collected in a folio.
3. The book was printed on fine quality folio paper.
4. The manuscript is written on folios of parchment.
5. The folio edition of the book was limited to only a few copies.