What does octavo mean?
Octavo is a bibliographic term for a book or printed work made from eight leaves. Each leaf is folded into three sections, so the finished volume ordinarily has sixteen pages. The word can refer either to the physical format itself or to a book size based on that format, as in a first edition “in octavo.” It is most useful when describing older books, manuscripts, and early printed editions, where the relationship between sheets, leaves, and pages can affect how a text is understood. In modern general speech, octavo is uncommon, but it remains standard in bibliographies, library catalogs, and the history of the book. Its name reflects the Latin octavus, meaning “eighth,” which in turn derives from the root for eight.
A book or printed work made from eight leaves, with each leaf folded into three sections to form sixteen pages.
"The early edition survives in octavo."
Used chiefly in bibliography and the history of printing; “in octavo” is a common bibliographic phrase.
Denoting a book or printed format consisting of eight leaves folded into sixteen pages.
"The catalogue describes the work as an octavo volume."
This adjectival use is established in bibliographic and book-history contexts.
The plural is used when referring to multiple books or editions in this format.
"Several early octavos are held by the library."
Octavo literally describes a book made from eight leaves, but each folded leaf creates sixteen pages—so the name refers to the sheets, not the visible pages.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does octavo come from?
English octavo comes through French from Latin octavus, meaning “eighth.” The Latin adjective is based on octō, “eight,” the same root found in related forms such as octave and octet. In bookmaking, the term ultimately refers to eight folded leaves rather than sixteen pages, because each leaf contains two pages and is folded to create three sections.
How octavo is actually used
Primarily used in bibliography, librarianship, book history, and descriptions of editions or printed materials. It is a specialist term rather than ordinary everyday vocabulary.
Easily confused with octavo
An octavo is a book format made from eight leaves, whereas an octave is a musical or poetic interval of eight notes or a related musical range.