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Synonyms for Backup (same or very similar meaning)

WordNet sense 1 (someone who takes the place of another (as when things get dangerous or difficult)):
fill-in, relief, reliever, stand-in, substitute, backup man

WordNet sense 2 (a subordinate musical part; provides background for more important parts):
accompaniment, support, musical accompaniment

WordNet sense 3 ((computer science) a copy of a file or directory on a separate storage device):
computer backup

WordNet sense 4 (the act of providing approval and support):
backing, championship, patronage, championship

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