A reserve or substitute.
reinforcements
A copy of a file or record, stored separately from the original, that can be used to recover the original if it is destroyed or damaged.
An accumulation of material caused by a (partial) obstruction or (complete) blockage of the flow or movement of the material, or an accumulation of material that causes an overflow due to the flow being greater than the maximum possible flow.
Supporting, reinforcing; (music) of or related to accompaniment
Standby, reserve or extra.
That is intended as a backup.
Defense or support of some cause.
A competition to determine a champion, especially the final of a series of competitions.
The position of champion, or winner.