A queue (in this sense) is a temporary holding place for data.

and the dead-letter queue uses exactly the same technical mechanisms as the acceptable messaging queues, it just doesn't have an active server to process the queue members. So it gets called a queue like the others even though, as BY points out, queues usually offer some hope of being served (except the ones I join).

quiesce - to make dormant, inactivate. Widely used in IT industry, usually in the sense of temporarily placing active processes or applications on hold to allow some housekeeping or upgrade. My online Pocket Oxford has quiescent but not quiesce.

Rod