backup
Americannoun
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a person or thing that supports or reinforces another.
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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.
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an overflow or accumulation due to stoppage, malfunctioning, etc..
a sewage backup; a backup of cars at the tollbooth.
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a person, plan, device, etc., kept in reserve to serve as a substitute, if needed.
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Computers.
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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.
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a procedure to follow in such an event.
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Bowling. a ball that curves in a direction corresponding to the bowling hand of the bowler.
adjective
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(of a person, plan, device, etc.) held in reserve as a substitute if needed.
a backup driver; a backup generator.
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performing a secondary or supporting function.
A drummer and guitarist are the singer's backup musicians.
Usage
See login.
Etymology
Origin of backup
1775–85, noun use of verb phrase back up
Explanation
Backup is what someone gives when they help or support you. A brand new doctor might need some backup in the emergency room for the first few weeks. Use the noun backup when you talk about extra assistance or help. Police officers call for backup when they're not sure they can handle a situation on their own, and store cashiers need backup when things get busy and customers start lining up. Another kind of backup is the one you do on your computer — in this case, a backup is the process of copying your data in case you lose the original files.
Vocabulary lists containing backup
Computer Science and Technology - Introductory
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Computer Science and Technology - Middle School
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Computer Science and Technology - High School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Paci was a backup quarterback for the New York Jets and cuts an imposing figure at 6’4.”
From The Wall Street Journal • May 23, 2026
Cummins’ AI-related business—supplying backup power for data centers —has sent the stock’s valuation to levels not seen in a decade.
From Barron's • May 21, 2026
In other words, the market has had backup supplies to draw on.
From MarketWatch • May 18, 2026
After he warmed up at a gas station, backup finally arrived to fix the brakes, and he returned to the trailer and got on his way.
From Slate • May 13, 2026
The girls stand behind me protectively, like backup dancers.
From "The House That Lou Built" by Mae Respicio
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
