- 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
- a large sheet of paper folded once, so that it forms two leaves, or four pages, of a book, manuscript, etc.
- a large size of book, about 12 by 15 inches, made of sheets folded in this way
- a leaf of a manuscript, book, etc. numbered on only one side
- the number of a page in a book, etc.
Origin of folioMiddle English from Classical Latin (in) folio, (in) a sheet, ablative of folium, a leaf (in LL, leaf of paper): see foliate
transitive verb-·li·oed·, -·lio·ing