backup

noun

1. an accumulation caused by clogging or a stoppage"a traffic backup on the main street"
2. someone who takes the place of another (as when things get dangerous or difficult)"the star had a stand-in for dangerous scenes"
3. a musical part (vocal or instrumental) that supports or provides background for other musical parts
4. (computer science) a copy of a file or directory on a separate storage device"he made a backup in case the original was accidentally damaged or erased"
5. the act of providing approval and support"his vigorous backing of the conservatives got him in trouble with progressives"