(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"
an accumulation caused by clogging or a stoppage; "a traffic backup on the main street"; "he discovered a backup in the toilet"
substitute a person or thing for (another that is broken or inefficient or lost or no longer working or yielding what is expected); "He replaced the old razor blade"; "We need to replace the secretary that left a month ago"; "the insurance will replace the lost income"; "This antique vase can never be replaced"
put something back where it belongs; "replace the book on the shelf after you have finished reading it"; "please put the clean dishes back in the cabinet when you have washed them"