n. A sheet of paper folded once, usually through the shorter diameter, so as to consist of two equal leaves.n. A book or other publication, or a blank book, etc., consisting of sheets or of a single sheet folded once.n. The size of such a book, etc.: as, an edition of a work in folio. Abbreviated fol.: as, 3 vols.n. 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.n. In bookkeeping, a page of an account-book, or both the right- and left-hand pages numbered with the same figure.n. In printing, the number of a page, inserted at top or bottom.n. In law, a certain number of words taken as a basis for computing the length of a document.n. A wrapper or case for loose papers, sheet music, engravings, etc.: as, a music-folio.n. 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.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.