noun

backup

/ˈbækʌp/ · say it: BAK·up

a copy of data kept in case the original is lost

In Technology & Computing

In more detail

1. (noun) a copy of computer files or data stored separately as protection against loss

2. (noun) a person or thing ready to use if the main one fails

3. (noun) a traffic jam or line of vehicles moving slowly

4. (verb) to make a copy of computer files or data for safety

5. (verb) to move backward

6. (verb) to support someone or something

Examples

1. I keep a backup of all my important documents on an external drive.
2. The backup goalkeeper will play if the main goalkeeper gets injured.
3. There was a backup of traffic on the highway after the accident.

How to use backup

Backup as a noun refers to a protective copy of data, a substitute person or thing, or traffic congestion. As a verb, it means to create a copy (computing), move in reverse, or provide support. The computing sense is very common in modern contexts. The noun is often used attributively (backup plan, backup battery).

Common phrases

backup plan
backup copy
backup dancer
backup generator
backup quarterback
back up your files

Synonyms

copy · reserve · support · second · reinforce

Opposites

original · primary · main

Word family

back · backing

A common mistake

Learners sometimes use 'backup' when they mean 'back-up' (hyphenated adjective) or confuse it with 'back-down' (retreat in an argument). Also, some fail to distinguish between 'backup' as a count noun versus using it attributively.

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