Standby, reserve or extra.
Supporting, reinforcing; (music) of or related to accompaniment
That is intended as a backup.
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.
A reserve or substitute.
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.
Beyond what is due, usual, expected, or necessary; extraneous; additional; supernumerary.
Over the top; going beyond what is normal or appropriate, often in a dramatic manner.
Denotes more.
To an extraordinary degree.
A run scored without the ball having hit the striker's bat - a wide, bye, leg bye or no ball.
A supernumerary or walk-on in a film or play.
An extra edition of a newspaper, which is printed outside of the normal printing cycle, for example to report an important late-breaking event.
The state or trait of being over the top, of behaving in an overly dramatic manner.
Something additional, such as an item above and beyond the ordinary school curriculum, or added to the usual charge on a bill.
Something of an extra quality or grade.