Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

quinternion

A gathering consisting of five sheets folded once, and insetted. This was the form in which some manuscripts and early printed books, especially those of vellum, were assembled. The first and tenth, second and ninth, etc., leaves were conjugate. See also: QUATERNION SEXTERNION ; TERNION . (258 , 278 )