Meaning

noun the system of numbering pages

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

noun a book (or manuscript) consisting of large sheets of paper folded in the middle to make two leaves or four pages

originFrom Middle English folio (“leaf of a book”), borrowed from Medieval Latin foliō, Late Latin foliō, Latin foliō, the ablative singular form of Late Latin folium (“leaf or sheet of paper”), Latin folium (“leaf of a plant”), ultimately from Proto-Indo-European *bʰleh₃- (“bloom, flower”). Doublet of foil and folium, and distantly related to phyllo and phyllon. Senses 1, 2, 3.1, 5, and 6 relating to…

Etymology from Wiktionary, CC BY-SA 3.0