- folio
- mid-15c., from L.L. folio "leaf or sheet of paper," from L. folio, abl. of folium "leaf," from PIE *bhulyom "leaf" (cf. Gk. phyllon "leaf," Gael. bile "leaflet, blossom"), from base *bhel- (2) "to thrive, bloom, swell" (see bole). Ablative of location, since this was used in page references. Meaning "volume of the largest size" first attested 1620s.