a person or thing that supports or reinforces another.
a musician or singer or group of musicians or singers accompanying a soloist: a singer with a three-man backup that plays cello, bass, and guitar.
an overflow or accumulation due to stoppage, malfunctioning, etc.: a sewage backup; a backup of cars at the tollbooth.
a person, plan, device, etc., kept in reserve to serve as a substitute, if needed.
a copy or duplicate version, especially of a file, program, or entire computer system, retained for use in the event that the original is in some way rendered unusable.
a procedure to follow in such an event.
Bowling. a ball that curves in a direction corresponding to the bowling hand of the bowler.
(of a person, plan, device, etc.) held in reserve as a substitute if needed: a backup driver; a backup generator.
performing a secondary or supporting function: A drummer and guitarist are the singer's backup musicians.
- back up, backup
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use backup in a sentence
It typically takes days to get results back, and backups at labs can drag the process out for a week or two.New coronavirus tests promise to be faster, cheaper and easier | Jack J. Lee | August 31, 2020 | Science News
They have to be pretty confident they have someone to replace Mayer if they didn’t even get him to stay as a backup.TikTok’s most vocal defender is now its new interim CEO | Naomi Xu Elegant | August 27, 2020 | Fortune
Using new technologies and backup power sources, Winn said SDG&E has also taken steps to reduce the number of customers who lose power this year.
At the start of the Covid-19 outbreak, when my insurance wouldn’t allow me to get a backup supply of the insulin I need to live, I received eight vials in the mail from my friend Rena.How high prices for diabetes care amplify health inequities | Annalisa van den Bergh | July 15, 2020 | Quartz
As a backup, researchers should also consider using a less tested freeze-drying technique known as lyophilization.Scientists want to build a Noah’s Ark for the human microbiome | Carolyn Beans | June 11, 2020 | Science News
Sometimes, they had a backup aim if their main goal fell through as the night dragged on.The Craziest Date Night for Single Jews, Where Mistletoe Is Ditched for Shots | Emily Shire | December 26, 2014 | THE DAILY BEAST
In early October, Health Republic allowed me to submit a “grievance claim” which I filed, along with a pile of backup documents.
At 12:02 p.m., Wilson called in his location and asked the dispatcher for backup.
backup dancers materialize, sparking a torrent of eye-catching choreography.The Making of Kiesza: From Navy Sharpshooter to Beauty Queen to Pop Diva | Marlow Stern | October 20, 2014 | THE DAILY BEAST
She retreated into the lobby, but only to call for backup and an ambulance.Manhunt for a Cop-Hating Pennsylvania ‘Survivalist’ | Michael Daly | September 17, 2014 | THE DAILY BEAST
She could swap out a dead bot for a backup in five minutes flat, which is all that crowd-control would permit.
My cochlea struck twelve noon and a HUD appeared with my weekly backup reminder.
My next-most-recent backup was three years old, dating from the completion of my second symphony.
I stopped in front of the backup terminal in the gateway between Liberty Square and Fantasyland.
I had prepared a written synopsis of the events since her last backup for her, and she read it over the next couple days.
British Dictionary definitions for back up
(tr) to support or assist
(intr) cricket (of a nonstriking batsman) to move down the wicket in readiness for a run as a ball is bowled
(of water) to accumulate
(of traffic) to become jammed behind an accident or other obstruction
computing to make a copy of (a data file), esp for storage in another place as a security copy
printing to print the second side of (a sheet)
(intr, usually foll by on) Australian to repeat an action immediately
a support or reinforcement
a reserve or substitute
(as modifier): backup troops
US and Canadian
musical accompaniment, esp for a pop singer
(as modifier): backup singer
the overflow from a blocked drain or pipe
computing a file or set of files copied for security purposes
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Other Idioms and Phrases with backup
Move or drive a vehicle backward, as in He told her to back up into the garage. [First half of 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.