backup

American  

[bak-uhp] / ˈbækˌʌp /

noun

1. a person or thing that supports or reinforces another.

2. 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.

3. an overflow or accumulation due to stoppage, malfunctioning, etc..

   a sewage backup; a backup of cars at the tollbooth.

4. a person, plan, device, etc., kept in reserve to serve as a substitute, if needed.

5. Computers.

   1. 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.

   2. a procedure to follow in such an event.

6. Bowling. a ball that curves in a direction corresponding to the bowling hand of the bowler.

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adjective

1. (of a person, plan, device, etc.) held in reserve as a substitute if needed.

   a backup driver; a backup generator.

2. 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.

Example Sentences

AI chip design companies, including Google and Nvidia, are using Intel as a backup manufacturer for advanced processors, a report says.

From Barron's • Jun. 8, 2026

Having previously attended Irish festivals which have contingency plans for rain, Cashell says crowds were left "confused as to how there was no backup plan".

From BBC • Jun. 5, 2026

Last month, Wilson told the New York Post that he received an offer from the New York Jets to serve as a backup to quarterback Geno Smith.

From Los Angeles Times • Jun. 4, 2026

Having a portfolio that is 100% in individual stocks sounds about as risky to me as you can get, especially at 73, with no partner for backup, and living in seemingly permanent economic instability.

From MarketWatch • Jun. 3, 2026

“I bet she has a backup charger,” Natalie said, sounding more bored than ever.

From "The Strangers" by Margaret Peterson Haddix

Related Words

• substitute