backup

n. copying of data in order for retrieval in the event of a malfunction (Computers); substitute; reserve, spare

In information technology, backup refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. These additional copies are typically called "backups." Backups are useful primarily for two purposes. The first is to restore a computer to an operational state following a disaster (called disaster recovery). The second is to restore small numbers of files after they have been accidentally deleted or corrupted. Backups are typically that last line of defense against data loss, and consequently the least granular and the least convenient to use.
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Noun
1. an accumulation caused by clogging or a stoppage; "a traffic backup on the main street"; "he discovered a backup in the toilet"
(hypernym) accretion, accumulation
(derivation) clog, choke off, clog up, back up, congest, choke, foul
2. someone who takes the place of another (as when things get dangerous or difficult); "the star had a stand-in for dangerous scenes"; "we need extra employees for summer fill-ins"
(synonym) stand-in, substitute, relief, reliever, backup man, fill-in
(hypernym) peer, equal, match, compeer
(hyponym) locum tenens, locum
3. a subordinate musical part; provides background for more important parts
(synonym) accompaniment, musical accompaniment, support
(hypernym) part, voice
(hyponym) descant, discant
4. (computer science) a copy of a file or directory on a separate storage device; "he made a backup in case the original was accidentally damaged or erased"
(synonym) computer backup
(hypernym) duplicate, duplication
(derivation) back up
(classification) computer science, computing
5. the act of providing approval and support; "his vigorous backing of the conservatives got him in trouble with progressives"
(synonym) backing, championship, patronage
(hypernym) blessing, approval, approving
(derivation) support, back up

n. backup, method of protection, copying of data in order for retrieval in the event of a malfunction, substitute (Computers); reserve, spare

n. backup system, system which allows data protection and restoration in the event of a computer crash