backup

Từ điển Oxford Advanced Learner 8th

back·up 7 [backup] BrE [ˈbækʌp] NAmE [ˈbækʌp] noun uncountable, countable
1. extra help or support that you can get if necessary
•The police had backup from the army.
•We can use him as a backup if one of the other players drops out.
•a backup power supply
2. (computing)a copy of a file, etc. that can be used if the original is lost or damaged
•Always make a backup of your work.
•a backup copy
see also ↑back up

Example Bank:
•The hospital has a backup power supply.
•The police called for backup from the army.
•We can use him as a backup if one of the team can't play.