Open English Wordnet
Nouns
(n)stand-in, substitute, relief, reliever, backup, backup man, fill-insomeone who takes the place of another (as when things get dangerous or difficult)“the star had a stand-in for dangerous scenes”, “we need extra employees for summer fill-ins”
(n)accompaniment, musical accompaniment, backup, supporta musical part (vocal or instrumental) that supports or provides background for other musical parts
(n)backup, computer backup(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”
(n)backing, backup, championship, patronagethe act of providing approval and support“his vigorous backing of the conservatives got him in trouble with progressives”