'Backup' vs 'Back Up': What's the Difference?

By Amy Gilmore, updated on July 16, 2023

Do you need to know the difference between 'backup' vs. 'back up?' If so, you are in the right place.

Here is the short answer: 

  • 'Backup' is a noun spelled as one word and means something that serves as an alternate or substitute.
  • 'Back up' is a verb spelled as two words and means to reverse or move back in position. 

There is much more to learn about these two terms, though. This guide contains definitions, examples, and usage tips to help you better understand the differences and how to use them accurately.

What is the Difference Between 'Backup' vs. 'Back Up?'

The significant difference between 'backup' vs. 'back up' is the part of speech you use them in.

  • 'Backup' is a noun that refers to something that serves as a substitute, alternate, or support to something.
  • When you use 'back up' as a verb means to reverse, go back to a previous point, or move back in position.

In the noun form, the term is always one word. However, the verb form is always two separate words.

When to Use 'Backup' vs. 'Back Up'

Now that you know the difference between these terms, let's take a closer look at when you use each. 

  • Use 'backup' as a noun to describe a copy of something used to save data.

For example, you could say:

We restored the latest backup because the site was not working correctly after the last update. 

  • Use 'back up' as a synonym of reverse.

For example, I might say:

Please back up, and I will bring your purchase to your vehicle. 

  • Use 'backup' to refer to someone who serves as a replacement for the main character.

For example, you might hear someone say:

You will be the backup. If the lead character cannot fulfill their role, you will need to step in. 

  • Use 'back up' to indicate the action of copying something.

For example, you could say:

You should back up the information on your computer to an external drive. 

  • Use 'backup' to refer to a stoppage.

For example, someone might say:

A backup in the sewage line is causing a horrible smell in the Italian restaurant. 

  • Use 'backup' to refer to someone who supports a main singer or musician.

For example, you might say:

I thought the backup singers were better than the star. 

Definition of 'Backup': What Does 'Backup' Mean?

According to the Merriam-Webster Dictionary, the definition of the noun form of 'backup' is:

  • Someone that acts as a substitute or replacement for the original

It can also mean:

  • A musical accompaniment or addition
  • Personnel who provide support to an operation or support staff
  • A stoppage or accumulation that stops the flow of something
  • A copy of data from a computer, website, or application

Synonyms of 'Backup'

  • Jam
  • Bottleneck
  • Snarl
  • Lock
  • Congestion
  • Tangle
  • Slowdown
  • Logjam
  • Delay
  • Stoppage
  • Crawl
  • Substitute
  • Alternate
  • Surrogate
  • Relief
  • Cover
  • Stand-in
  • Assistant
  • Support
  • Pinch hitter
  • Delegate
  • Agent
  • Agent-in-fact
  • Representative
  • Attorney
  • Locum tenens
  • Commissary
  • Assignee
  • Successor
  • Understudy
  • Proxy
  • Temporary
  • Replacement
  • Ad interim

Definition of 'Back Up': What Does 'Back Up' Mean?

The same publication defines 'back up' as a verb that means:

  • To accumulate or congest something

It can also mean:

  • To provide support for another player from a position in the rear of them
  • To hold something back
  • To make a copy so you have a reference if the information is lost
  • To make copies of all of the files or documents in a queue or on a computer

Synonyms of 'Back Up'

  • Testify
  • Support
  • Verify
  • Vouch
  • Validate
  • Vindicate
  • Attest
  • Affirm
  • Argue
  • Substantiate
  • Warrant
  • Prove
  • Guarantee
  • Declare
  • Avow
  • Authenticate
  • Prove
  • Document
  • Record

Pronunciation: How to Pronounce 'Backup' vs. 'Back Up'

Now, let's look at the pronunciation of these words. Learning pronunciation is an essential part of learning English, but it can also help you become a better writer.

So, here is a quick pronunciation guide.

  • Use this phonetic spelling to pronounce 'backup':


  • Use this phonetic spelling to pronounce 'back up':

bak up 

As you can see, you pronounce these terms the same way, whether you are using them as separate words or one.

Sample Sentences Using 'Backup' vs. 'Back Up'

Before you go, take a look at these sample sentences using 'backup' vs. 'back up' to ensure that you know how to use both terms.


  • Did you take a backup before you installed the latest update?
  • She didn't mind being the backup because she gained valuable experience studying under the star.
  • You should set your server up to take recurring backups.
  • Did you obtain a backup of the video recordings from the cloud server?
  • Having the backup allowed them to restore the application so they could remedy the issues.
  • The backup in the sewage line is causing problems for all of the homeowners on our street.

Back Up

  • You need to back up to the line before the server will bring your food out.
  • We need to back up the president on his decision to implement these changes throughout the organization.
  • Your claims are going to need to be backed up in court.
  • Back up and tell me what happened during the meeting this morning.
  • The construction crews are backing up traffic on the freeway unnecessarily because they closed all the lanes, and they haven't even begun working on the repairs.
  • If you back up the toilet, you will need to use a plunger to fix it.

Final Advice on the Difference Between 'Backup' vs. 'Back Up'

Finally, let's review what you learned about the difference between 'backup' vs. 'back up':

  • 'Backup,' written as one word, is a noun or an adjective that means an alternate or substitute or a stoppage.
  • 'Back up,' written as two words, is a verb that means to reverse or take a copy of data.

Due to these terms being spelled and pronounced similarly, it can be challenging to remember the difference. So, if you have trouble in the future, return to this lesson for a quick review.

Before you go, you should take a few minutes to look at some of the other confusing word guides here. They are an excellent way to expand your vocabulary and learn essential grammar rules.

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Written By:
Amy Gilmore
Amy Gilmore is one of the lead freelance writers for WritingTips.org. She has been a professional writer and editor for the past eight years. She developed a love of language arts and literature in school and decided to become a professional freelance writer after a demanding career in real estate. Amy is constantly learning to become a better writer and loves sharing tips with other writers who want to do the same.

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