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

Lakers 7-foot backup center Jaxson Hayes will be counted to get rebounds.

From Los Angeles Times • Apr. 14, 2026

Meanwhile, “if retirement falls short, the backup plan is often working longer — and that is not always realistic given the rapidly evolving workforce landscape.”

From MarketWatch • Apr. 9, 2026

The phenomenon is "something that we have not witnessed often," the mission's backup astronaut Jenni Gibbons told AFP.

From Barron's • Apr. 8, 2026

Over his two seasons as a backup, he scored just five points a game.

From The Wall Street Journal • Apr. 7, 2026

I bend over and reach into the bushes to get it, and when I stand backup, I lock eyes with her again.

From "Shouting at the Rain" by Lynda Mullaly Hunt

Related Words

• substitute