backup

1 of 2

noun

back·​up ˈbak-ˌəp 

often attributive

1

a

: one that serves as a substitute or support

I brought an extra pencil for backup.

a backup plan

b

: musical accompaniment

The tunes include banjo and guitar backup.

c

: additional personnel who provide assistance

The police officer called for backup.

2

: an accumulation caused by a stoppage in the flow

traffic backup

3

: a copy of computer data (such as a file or the contents of a hard drive)

I made a backup copy of the file.

also : the act or an instance of making a backup

back up

2 of 2

verb

backed up; backing up; backing up

intransitive verb

: to accumulate in a congested state

traffic backed up for miles

transitive verb

1

: to move into a position behind (a teammate) in order to assist on a play

2

: hold back sense 1

3

: to make a copy of (a computer file or data) to protect against accidental loss or corruption

Be sure to back up your work.

also : to make copies of all the files on (a device)

a program that automatically backs up your hard drive

Synonyms

Noun

• jam

Examples of backup in a Sentence

Noun

His role on the team is to be a backup to the regular quarterback.

We have an extra radio as a backup in case this one doesn't work.

We have an extra radio for backup.

He provides backup for the regular quarterback.

She sang backup on his CD.

Recent Examples on the Web

Noun

Most majors have a video review system as a backup to any close calls. —Chris Branch, New York Times, 7 July 2025

If their current cash cow model is under threat, new ones should be developed as a backup. —Zain Jaffer, Forbes.com, 7 July 2025

Verb

The hiker had turned around at Skeleton Point and was making his way back up the trail when the incident occurred, according to the NPS. —ABC News, 10 July 2025

Microsoft briefly took the top spot before the tech bubble, and then had to claw its way back up the ranks. —Jesse Pound, CNBC, 9 July 2025

Word History

First Known Use

Noun

1910, in the meaning defined at sense 1a

Verb

1801, in the meaning defined at intransitive sense

Rhymes for backup

• blowup
• breakup
• buildup
• checkup
• cleanup
• holdup
• hookup
• lineup
• lockup
• makeup
• markup
• pickup

Kids Definition

backup

1 of 2 noun

back·​up ˈbak-ˌəp 

1

: a person or thing that takes the place of or supports another

has a backup in case he gets sick

2

: a gathering or piling up because the flow has been stopped

a traffic backup

3

: a copy of a computer file to protect against loss of data

also : the act or an instance of making a backup

back up

2 of 2 verb

1

: to gather or pile up because the flow has been stopped

traffic backed up for miles

2

: to make a copy of (as a computer file) to protect against loss of data