folio

noun pl. folios

Bookkeeping a page of a ledger, or facing pages with the same number
Law a set number of words (100 in the U.S., 72 or 90 in England) considered as a unit of measuring the length of a legal or official document
Printing
1. a large sheet of paper folded once, so that it forms two leaves, or four pages, of a book, manuscript, etc.
2. a large size of book, about 12 by 15 inches, made of sheets folded in this way
3. a leaf of a manuscript, book, etc. numbered on only one side
4. the number of a page in a book, etc.

adjective

having sheets folded once; of the size of a folio

transitive verb folioed, folioing

to number the pages of (a book, etc.) consecutively; page

See folio in American Heritage Dictionary 4