Meaning of OCTAVO in English

OCTAVO

adj having eight leaves to a sheet; as, an octavo form, book, leaf, size, ·etc.

2. octavo ·noun a book composed of sheets each of which is folded into eight leaves; hence, indicating more or less definitely a size of book so made;

— usually written 8vo or 8°.

Webster English vocab.      Английский словарь Webster.