n.
an accumulation caused by clogging or a stoppage
"a traffic backup on the main street"; "he discovered a backup in the toilet"
someone who takes the place of another (as when things get dangerous or difficult)
同义词：stand-insubstitutereliefrelieverbackup manfill-in
a subordinate musical part; provides background for more important parts
同义词：accompanimentmusical accompanimentsupport
(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"
同义词：computer backup
the act of providing approval and support
同义词：backingchampionshippatronage
