Folios meaning : A leaf of a book or manuscript A page of a book, that is, one side of a leaf of a book. A page number. The even folios are on the left-hand pages and the odd folios on the right-hand pages. A sheet of paper folded in half. (books) A book made of sheets of paper each folded in half (two leaves or four pages to the sheet); hence, a book of the largest kind, exceeding 30 cm in height. A page in an account book; sometimes, two opposite pages bearing the same serial number. (19th to 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. A wrapper for loose papers.