Octavo n. : 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¡.

Octavo a. : Having eight leaves to a sheet; as, an octavo form, book, leaf, size, etc.

Example:
has anyone used the Nady U-81-Octavo 8 Channel UHF Lavalier System? Is it any good?

Taxonomy
Octavo Editions, preservation, rare books, Digital Rare Books, facsimile, advanced technology, seminal ideas, inspiration, discovery, audiences, monuments, science and culture, personal computer, CD-ROM, Adobe PDF, zoom, rare materials, manuscripts.

Defination from the web:
Publishes digital editions of rare books and manuscripts.