[fo.lio] n, pl fo.li.os [ME, fr. L, abl. of folium] (1447) 1 a: a leaf esp. of a manuscript or book b: a leaf number c: a page number d: an identifying reference in accounting used in posting
2. a: a sheet of paper folded once b: a case or folder for loose papers 3 a: the size of a piece of paper cut two from a sheet; also: paper or a page of this size b: a book printed on folio pages c: a book of the largest size
4: a certain number of words taken as a unit or division in a document for purposes of measurement or reference
[2]folio vt (1858): to put a serial number on each leaf or page of