What is the meaning of Backup?

A reserve or substitute.

A copy of a file or record, stored separately from the original, that can be used to recover the original if it is damaged or destroyed.

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.

Reinforcements.

Any support or extra help.

Accompaniment.

Corroboration.

Standby, reserve or extra.

That is intended as a backup.

Supporting, reinforcing; of or related to accompaniment

Alternative form of back up

backup

backup (copy of file or record)

Source: wiktionary.org