noun, often attributive
back·​up | \ ˈbak-ˌəp How to pronounce backup (audio) \

Definition of backup

 (Entry 1 of 2)

1a : 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

backed up; backing up; backing up

Definition of back up (Entry 2 of 2)

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
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

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Synonyms for backup

Synonyms: Noun

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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.
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Recent Examples on the Web: Noun Jalyn Holmes, who is the likely backup to Hunter at right defensive end, did not have a sack last season. Steve Silverman, Forbes, 27 May 2021 The only Mavericks player who has been part of more than one Dallas playoff run is Dwight Powell, who was a backup on the low-seed 2015 and 2016 teams that were quickly dispatched from the playoffs. Brad Townsend, Dallas News, 20 May 2021 An early enrollee in 2020, Denis is the backup on paper entering the offseason. oregonlive, 19 May 2021 But adding a graduate transfer who has been a career backup wasn’t the big splash Holtmann sought. Stephen Means, cleveland, 14 May 2021 Purdy has the athleticism and accuracy to make it to the NFL and be a backup in the league. Jeremy Cluff, The Arizona Republic, 10 May 2021 Brissett, who joined Miami after signing a one-year deal this offseason that could pay him $7.5 million, is a capable backup. Omar Kelly,, 4 May 2021 Lekkas was the backup for the Sabres AHL team in Rochester and is 1-4-1 with a .863 save percentage with a 4.32 goals-against average. Joe Yerdon, Star Tribune, 3 May 2021 Eubanks has been the top backup for Poeltl, and the duo has been a productive one. Jeff Mcdonald, San Antonio Express-News, 2 May 2021 Recent Examples on the Web: Verb But none of the initiatives relate directly to LGBTQ language, and others around baseball say it’s important to back up strong internal work with external support, such as a pride game. Sam Blum, Dallas News, 31 May 2021 But lithium, a relatively rare metal that’s only mined in a handful of countries, is too scarce and expensive to back up the world’s utility grids. Robert F. Service, Science | AAAS, 27 May 2021 Peker, who is believed to be currently residing in Dubai, has not so far produced documentary evidence to back up his allegations. Suzan Fraser, Star Tribune, 26 May 2021 So after criticizing his own play afterward, Davis vowed to back up his honest words with tangible action. Mark Medina, USA TODAY, 26 May 2021 Millsap lowered his shoulder and powered into Lillard, forcing Lillard to back up and eventually fall backward in an attempt to draw a charge. oregonlive, 25 May 2021 Wiseman will likely back up Looney if the Warriors don’t find a palatable trade offer for him. Connor Letourneau, San Francisco Chronicle, 22 May 2021 Womble said that Brown ignored deputies’ commands to stop, continued to back up, and then put the car in drive., 18 May 2021 The service can back up everything stored on an iPhone or Mac computer, and can reveal the current location of a user’s Apple devices. New York Times, 17 May 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'backup.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of backup


1910, in the meaning defined at sense 1a


1801, in the meaning defined at intransitive sense

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Statistics for backup

Last Updated

5 Jun 2021

Cite this Entry

“Backup.” Dictionary, Merriam-Webster, Accessed 15 Jun. 2021.

Style: MLA
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More Definitions for backup



English Language Learners Definition of backup

: a person or thing that can be used to replace or support another person or thing
: help or support provided by additional people or things
US : a situation in which the flow of something (such as traffic) becomes blocked


back·​up | \ ˈbak-ˌəp How to pronounce backup (audio) \

Kids Definition of backup

1 : a person who takes the place of or supports another The guard called for a backup.
2 : a situation in which the flow of something becomes blocked
3 : a copy of information stored on a computer


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