backup
名词 backup:
an accumulation caused by clogging or a stoppage
someone who takes the place of another (as when things get dangerous or difficult)
同义词:stand-in, substitute, relief, reliever, backup man, fill-in
a subordinate musical part; provides background for more important parts
同义词:accompaniment, musical accompaniment, support
(computer science) a copy of a file or directory on a separate storage device
同义词:computer backup
the act of providing approval and support
同义词:backing, championship, patronage