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
backed up; backing up; backing up
: to accumulate in a congested state
traffic backed up for miles
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
Synonyms
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
PCMAG, 6 Nov. 2024
Many voting locations will offer paper ballots as a backup should voting machines malfunction, Brennan Center for Justice attorney Derek Tisler told ABC News.
—Conor Murray, Forbes, 5 Nov. 2024
Harold Gutmann, The Mercury News, 16 Nov. 2024
Shares have been especially volatile around the election, with the stock closing down nearly 23% Thursday before popping back up 18% in Friday afternoon trading.
—Rocio Fabbro, Quartz, 8 Nov. 2024
See all Example Sentences for backup 
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Noun
Many cloud backup solutions are compromised when ransomware deletes backups.
—PCMAG, 6 Nov. 2024
Many voting locations will offer paper ballots as a backup should voting machines malfunction, Brennan Center for Justice attorney Derek Tisler told ABC News.
—Conor Murray, Forbes, 5 Nov. 2024
Verb
Kenney, who came to The Farm from Fargo, North Dakota but spent his first three years either injured or backing up current Los Angeles Rams kicker Joshua Karty, then nailed a career-best kick on Senior Day, sending the players and a small group of students storming onto the field.
—Harold Gutmann, The Mercury News, 16 Nov. 2024
Shares have been especially volatile around the election, with the stock closing down nearly 23% Thursday before popping back up 18% in Friday afternoon trading.
—Rocio Fabbro, Quartz, 8 Nov. 2024
See all Example Sentences for backup
Articles Related to backup
Dictionary Entries Near backup
Cite this Entry
“Backup.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/backup. Accessed 28 Nov. 2024.
Copy CitationKids 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 verb1
: 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
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