Jacket: The paper cover sometimes called the "dust cover" of a hardbound book.
Job Number: A number assigned to a printing project used for record keeping and job tracking. Also used to retrieve old jobs for reprints or reworking by customer.
Jog: To vibrate a stack of finished pages so that they are tightly aligned for final trimming.
Jogger: Vibrating, sloping platform that evens up the edges of stacks of paper.