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 New Orleans Saints backup quarterback Jameis Winston walked up to starting quarterback Drew Brees on the sideline. Amie Just | Staff Writer,, "Saints eliminated by Bucs in divisional round heartbreaker; here's how it happened," 17 Jan. 2021 Mariota, now a backup for his second NFL team, may or may not start depending on the health status of Raiders starter Derek Carr, who despite a groin injury became a full participant in practice on Wednesday. Safid Deen,, "Tua Tagovailoa appreciates friendship with Marcus Mariota; both could make history in Dolphins-Raiders matchup," 24 Dec. 2020 Dussie dances her way through a lot of this movie as a backup for Ma Rainey and her band. Kathleen Newman-bremang,, "Ma Rainey’s Black Bottom Star Taylour Paige On That Chadwick Boseman Scene You Can’t Stop Thinking About," 21 Dec. 2020 Other contributors not previously listed as unavailable include receiver Chris Booker, backup quarterback Gunnar Hoak and safety Bryson Shaw. Nathan Baird, cleveland, "Which Ohio State football players are unavailable against Northwestern in the Big Ten championship game?," 19 Dec. 2020 Linz was a light-hitting backup for most of his seven-year career, batting .235 with 11 homers for the Yankees, Phillies and Mets. Ben Walker,, "Baltimore native and ex-Yankee Phil Linz, key player in ’64 harmonica flap, dies at 81," 12 Dec. 2020 Colts backup quarterback Jacoby Brissett is a vulture. Eddie Brown, San Diego Union-Tribune, "Fantasy Football Week 13: Start and Sit," 5 Dec. 2020 After contributing 11 tackles and 4.5 tackles for a loss as a backup last season, Allen has emerged as one of the most consistent and most disruptive players in the Tide front seven as a redshirt junior. Matt Zenitz |, al, "Alabama’s lesser-known Baton Rouge linebacker has become valued contributor," 4 Dec. 2020 Following Penix’s late-third-quarter injury, backup quarterback Jack Tuttle came in and completed all five of his passes, plus a two-point conversion to put IU ahead 17-3. Jon Blau, The Indianapolis Star, "Running game, defense step up for No. 12 Hoosiers after Michael Penix injury," 28 Nov. 2020 Recent Examples on the Web: Verb Raffensperger declined throughout the call to do so, saying the data does not back up the president's claims. Todd Spangler, Detroit Free Press, "Trump continues to press unsubstantiated Michigan claims in Georgia phone call," 5 Jan. 2021 The Giants, preferring top catching prospect Joey Bart to open the season in the minors, had been seeking a veteran catcher to back up Posey. John Shea,, "New Giants catcher Curt Casali recruited Mike Yastrzemski, will he recruit Trevor Bauer?," 5 Jan. 2021 Trump also leaned heavily on conspiracy theories to back up his claim, claiming ballots were burned and shredded and that dead people somehow voted. Asia Ewart,, "Will Trump’s Leaked Call Pressuring Georgia’s Secretary Of State Lead To Prosecution?," 4 Jan. 2021 Iowa State has serious firepower to back up their prowess this season. oregonlive, "Why Mario Cristobal believes Iowa State is ‘the most physical team’ Oregon Ducks have faced in years," 30 Dec. 2020 Huntley will back up quarterback Lamar Jackson for the second straight game. Daniel Oyefusi,, "Ravens DE Calais Campbell active, CB Marcus Peters inactive Sunday; Giants QB Daniel Jones active, will start," 27 Dec. 2020 The story attempts to strike a balance between science and journalism, with hard measurements to back up more traditional, on-the-ground reporting. Derek Watkins, New York Times, "How We Reported on Pollution in New Delhi Through Two Children," 24 Dec. 2020 In the video, Santos calls for a medic and back up. N'dea Yancey-bragg, USA TODAY, "Texas police release body camera video of fatal shooting of Joshua Feast," 23 Dec. 2020 If a vehicle tail pipe becomes buried by snow, slush, mud or water, exhaust can back up into the vehicle cabin and cause death from carbon monoxide poisoning. Tim Macwelch, Popular Science, "10 winter survival tips everyone should know," 15 Dec. 2020

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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Time Traveler for backup

Time Traveler

The first known use of backup was in 1801

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Statistics for backup

Last Updated

24 Jan 2021

Cite this Entry

“Backup.” Dictionary, Merriam-Webster, Accessed 26 Jan. 2021.

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More Definitions for backup


How to pronounce back up (audio)

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

: a person who takes the place of or supports another The guard called for a backup.

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Comments on backup

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