folio

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large sheet of paper folded once in the middle, making two leaves or four pages of a book or manuscript.
• noun A book or manuscript of the largest common size, usually about 38 centimeters (15 inches) in height, consisting of such folded sheets.
• noun A leaf of a book numbered only on the front side.
• noun A number on such a leaf.
• noun A page number.
• noun Law A specific number of words used as a unit for measuring the length of the text of a legal document.
• transitive verb To number consecutively the pages or leaves of (a book, for example).

from The Century Dictionary.

• In printing, to number the pages of, as a book or periodical; page; paginate.
• In law-copying, to mark with its proper figure the end of every folio in; in law-printing, to mark with its proper figure the space that should be occupied by a folio in. See folio, n., 7.
• noun A sheet of paper folded once, usually through the shorter diameter, so as to consist of two equal leaves.
• noun A book or other publication, or a blank book, etc., consisting of sheets or of a single sheet folded once.
• noun The size of such a book, etc.: as, an edition of a work in folio. Abbreviated fol.: as, 3 vols.
• noun One of several sizes of paper adapted for folding once into well-proportioned leaves, whether intended for such use or not, distinguished by specific names.
• noun In bookkeeping, a page of an account-book, or both the right- and left-hand pages numbered with the same figure.
• noun In printing, the number of a page, inserted at top or bottom.
• noun In law, a certain number of words taken as a basis for computing the length of a document.
• noun A wrapper or case for loose papers, sheet music, engravings, etc.: as, a music-folio.
• noun In abundance; in great style (Nares); but, perhaps, in separate leaves; in flakes or fragments.
• Pertaining to or having the form of a folio; folded or adapted for folding once; consisting of leaves formed by one folding: as, a sheet or book of folio size; a folio sheet, page, newspaper, or book.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To put a serial number on each folio or page of (a book); to page.
• adjective Formed of sheets each folded once, making two leaves, or four pages. See folio, n., 3.
• noun A leaf of a book or manuscript.
• noun A sheet of paper once folded.
• noun A book made of sheets of paper each folded once (four pages to the sheet); hence, a book of the largest kind. See Note under Paper.
• noun (Print.) The page number. The even folios are on the left-hand pages and the odd folios on the right-hand.
• noun A page of a book; (Bookkeeping) a page in an account book; sometimes, two opposite pages bearing the same serial number.
• noun (Law) A leaf containing a certain number of words, hence, a certain number of words in a writing, as in England, in law proceedings 72, and in chancery, 90; in New York, 100 words.
• noun a flat writing paper, usually 17 by 24 inches.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A leaf of a book or manuscript.
• noun paper A sheet of paper once folded.
• noun books A book made of sheets of paper each folded once (two leaves or four pages to the sheet); hence, a book of the largest kind, exceeding 30 cm in height.
• noun printing The page number. The even folios are on the left-hand pages and the odd folios on the right-hand.
• noun A page of a book.
• noun accounting a page in an account book; sometimes, two opposite pages bearing the same serial number.
• noun law, dated, 19th century, early, 20th century A leaf containing a certain number of words, hence, a certain number of words in a writing, as in England, in law proceedings 72, and in chancery, 90; in New York, 100 words.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a sheet of any written or printed material (especially in a manuscript or book)
• noun a book (or manuscript) consisting of large sheets of paper folded in the middle to make two leaves or four pages
• noun the system of numbering pages