'backup' definitions:

Definition of 'backup'

From: WordNet
noun
An accumulation caused by clogging or a stoppage; "a traffic backup on the main street"; "he discovered a backup in the toilet"
noun
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, backup man, fill-in]
noun
A musical part (vocal or instrumental) that supports or provides background for other musical parts [syn: accompaniment, musical accompaniment, backup, support]
noun
(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: backup, computer backup]
noun
The act of providing approval and support; "his vigorous backing of the conservatives got him in trouble with progressives" [syn: backing, backup, championship, patronage]

Definition of 'backup'

From: GCIDE
  • backup \back"up\, n.
  • 1. anything kept in reserve to serve as a substitute in case of failure or unavailability of the normal or primary object; -- used for devices, plans, people, etc. Also used attributively; as, there was no backup for the electrical supply; a backup motor; a backup generator. [PJC]
  • 2. (Music) a musician or group of musicians accompanying a soloist, whether vocalists or instrumentalists.
  • Syn: accompaniment. [PJC]
  • 3. a person or group of persons serving as reinforcement for another or others; as, the policeman called for backup when he was fired on. [PJC]
  • 4. an accumulation, overflow, or reverse flow (in traffic or a liquid flow system) caused by a stoppage or other malfunction. [PJC]
  • 5. (Computers) A copy of a program or data from a computer onto a data-storage medium, usually one that may be removed to safe storage at a distance from the computer; it is used to preserve data for use in the contingency that the original data on the computer may be lost or become unusable. A backup that is removed from the building housing the computer system (to provide protection against loss of data in a disastrous event such as a fire) is called off-site backup. Also used attributively; as, backup copy. [PJC]
  • 6. (Computers) The act or process of creating a backup[5]; as, they performed a full system backup every weekend. [PJC] Backward