folio
noun
[ ˈfəʊlɪəʊ ]
• an individual leaf of paper or parchment, either loose as one of a series or forming part of a bound volume, which is numbered on the recto or front side only.
• a sheet of paper folded once to form two leaves (four pages) of a book.
Origin:
late Middle English: from Latin, ablative of folium ‘leaf’, in medieval Latin used in references to mean ‘on leaf so-and-so’. The original sense of in folio (from Italian in foglio ) was ‘in the form of a full-sized sheet or leaf folded once’ (designating the largest size of book).
