1. octavo - Noun
2. octavo - Adjective
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¡.
Having eight leaves to a sheet; as, an octavo form, book, leaf, size, etc.
Source: Webster's dictionaryEvil knows of the Good, but Good does not know of Evil. Knowledge of oneself is something only Evil has. - The First Octavo Notebook. Franz Kafka
Darnton, (1979), p. 7. As the Encyclopédie gained popularity, it was published in quarto and octavo editions after 1777. Source: Internet
The Houghton Library copy of this text (STC 22330) has vertical chain lines and watermarks in the upper inner margin, just as one would expect to find in an octavo. Source: Internet
His chief prose works are a standard publication in seven octavo volumes of the Methodist Book Concern, New York. Source: Internet
The quarto and octavo editions were much less expensive than previous editions, making the Encyclopédie more accessible to the non-elite. Source: Internet