folio

Short definition from Wiktionary

Noun

1. 1
   A leaf of a book or manuscript.
2. 2
   A page of a book, that is, one side of a leaf of a book.
3. 3
   A page number. The even folios are on the left-hand pages and the odd folios on the right-hand pages.
4. 4
   A sheet of paper folded in half.
5. 5
   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 centimetres in height.
6. 6
   A wrapper for loose papers.
7. 7
   A page in an account book; sometimes, two opposite pages bearing the same serial number.
8. 8
   A protective case with a flap that folds to cover the screen of a mobile device.
9. 9
   A leaf containing a certain number of words; hence, a certain number of words in a piece of writing, as in England, in law proceedings 72, and in chancery, 90; in New York, 100 words.

Verb

1. 1
   To put a serial number on (a folio or page, or on all the folios or pages of a book); to foliate, to page.