Folio
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
A leaf
The references to the writings of the older law authors are usually made by citing the folio, as it was the ancient custom to number the folio instead of the page, as is done in modern books. A certain number of words specified by statute as a folio.
Wharton.
Originating, undoubtedly, in some estimate of the number of words which a folio ought to contain.