1Something that is not a book, especially a publication or library holding (as a manuscript, microfilm, audio-visual tool, etc.).
2A book of little or no literary merit, a potboiler, picture book, etc.
Of, relating to, using, or designating something (especially a publication or other communicative medium) that is not a book, or not a book of any literary merit. Chiefly attributive.
1920s. From non- + book.