A book or manuscript of the third largest standard size, usually measuring 20-25 cm (8-9 1/2 inches) in height, and 13-15 cm (5-6 inches) in width, which is composed of sheets of paper folded into eight leaves ("oct-" is from Latin for eight). The plural form is octavos. Abbreviated o, O, O., oct., Oct., and 8vo. Also called eightvo.(pr. ahk-TAH-voh)Also see bookbinding, duodecimo, folio, quarto, rotulus, sextodecimo, signature, text, tricesimo-segundo, and vicesimo-quarto.