Noun
a book (or manuscript) consisting of large sheets of paper folded in the middle to make two leaves or four pages; "the first folio of Shakespeare''s plays"

Noun
a sheet of any written or printed material (especially in a manuscript or book)

Noun
the system of numbering pages

n.
A leaf of a book or manuscript.

n.
A sheet of paper once folded.

n.
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.

n.
The page number. The even folios are on the left-hand pages and the odd folios on the right-hand.

n.
A page of a book; (Bookkeeping) a page in an account book; sometimes, two opposite pages bearing the same serial number.

n.
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.

Folio

A leaf of a book or manuscript.