Word of the Week

folio: A single leaf of parchment or paper (from folium = leaf) which has a front or recto side (also known as the obverse), and a back or verso side (also known as the reverse); hence one folio comprises what in normal parlance is two pages.

From: T.S. Haskett's Some Notes on Palaeography, Codicology and Diplomatics, 2001.