Mid 17th century; earliest use found in Thomas Urquhart (1611–1660), author and translator. From post-classical Latin quinternio set of five double sheets of paper, i.e. twenty pages from classical Latin quīntus fifth + -ernio (in post-classical Latin quaternio).
Definition of quinternion in US English:
quinternion
nounk(w)ɪnˈtəːnɪən
Printing
A set or gathering of five sheets of paper.
Origin
Mid 17th century; earliest use found in Thomas Urquhart (1611–1660), author and translator. From post-classical Latin quinternio set of five double sheets of paper, i.e. twenty pages from classical Latin quīntus fifth + -ernio (in post-classical Latin quaternio).