backup (
http://definr.com/backup)
n 1: someone 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" [syn:
stand-in,
substitute,
relief,
reliever,
backup man,
fill-in]
2: (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" [syn: {computer
backup}]