What is "folio post"

Folio \Fol"io\, n.; pl. Folios. [Ablative of L. folium leaf. See 4th Foil.]

1. A leaf of a book or manuscript.

2. A sheet of paper once folded.

3. 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.

4. (Print.) The page number. The even folios are on the left-hand pages and the odd folios on the right-hand.

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

6. (Law) 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 post, a flat writing paper, usually 17 by 24 inches.

n. (context paper English) A flat sheet of writing paper, usually 17 by 24 inches.