Definition of octavo in English:
noun (plural octavos)
1A size of book page that results from the folding of each printed sheet into eight leaves (sixteen pages).
- Folded one more time, the sheet produces a book-sized format call an octavo.
- Faulkner's monument is the edition of Swift's Works issued in twenty octavo volumes in 1772.
- The first number of the Boston Journal of Natural History appeared in 1834 and continued through seven octavo volumes until it was declared complete in 1863.
late 16th century: from Latin in octavo 'in an eighth', from octavus 'eighth'.