backup

The word “backup” means a person, plan, or system kept in reserve in case the main one fails. In plain terms, something held in reserve for support, or a saved copy of data, or a jam that stops normal flow.

“Backup” is pronounced BAK-uhp (/ˈbækˌʌp/ in IPA).

Here is “backup” used in a sentence: “Always bring a backup charger when you travel.”

Words with a similar meaning to “backup” include reserve and spare.

“Backup” is a noun.

“Backup” is a fairly common word in modern English, usually learned at around the B2 level.

“Backup” has 3 distinct senses listed in this dictionary. The most common is: a person, plan, or system kept in reserve in case the main one fails.

'Backup' as one word is a noun or adjective, as in 'make a backup' or 'a backup plan'. 'Back up' as two words is the verb, as in 'back up your files'. The hyphenated 'back-up' is an older or British variant of the noun, though the single word is now most common.

A 'backup' is a copy of digital files kept separately so the originals can be restored if lost or damaged, and it is usually meant to be current and recoverable. An 'archive' is long-term storage of older files that are no longer in active use but kept for records, so a backup restores what you use now while an archive preserves the past.

In the 'reserve' sense, 'backup' often appears in 'backup plan', 'backup singer', and 'call for backup'. In the digital sense, it pairs with verbs such as 'create a backup', 'restore from a backup', and 'automatic backup'.