From Longman Dictionary of Contemporary Englishbackupback‧up /ˈbækʌp/ ●○○ noun 1 [countable] something that you can use to replace something that does not work or is lost Always have a backup plan. a backup generator2 [countable] a copy of a computer document, program etc, which is made in case the original becomes lost or damaged Make a backup of any work you do on the computer.3 HELP[uncountable] people or things that can be used to provide support and help if they are needed Army units can only operate if they have sufficient backup. a backup team4 [countable] American English someone who will play in a sports team if one of the other players is injured or ill SYN reserve a backup goalie
Examples from the Corpus
backup• But he had a backup plan; you had to if you came this far.• These allow the user to delete and rename files or make a backup copy.• His father and Mr Abrey fill in as relief drivers and backup.• A good backup team might help as well!• Standard brakes include power, vented front discs and rear drums with anti-lock backup.• Several police cars provided backup for the officers.• His top backup, Donovan Ricketts, is also out with a pelvic injury.From Longman Business Dictionarybackupback‧up /ˈbækʌp/ noun [countable] COMPUTING a copy of information held on a computer that is put onto a DISK so that the information is not lost if there is a problem with the computerTake a backup copy of the file to be converted. 