backupn.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.()2. (Music) a musician or group of musicians accompanying a soloist, whether vocalists or instrumentalists.()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.()4. an accumulation, overflow, or reverse flow (in traffic or a liquid flow system) caused by a stoppage or other malfunction.()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.()6. (Computers) The act or process of creating a backup{5}; as, they performed a full system backup every weekend.()adv.[Back, adv. + -ward.]1. With the back in advance or foremost; as, to ride backward.()2. Toward the back; toward the rear; as, to throw the arms backward.()3. On the back, or with the back downward.()Thou wilt fall backward. (Shak.)4. Toward, or in, past time or events; ago.()Some reigns backward. (Locke.)5. By way of reflection; reflexively.(Sir J. Davies.)6. From a better to a worse state, as from honor to shame, from religion to sin.()The work went backward. (Dryden.)7. In a contrary or reverse manner, way, or direction; contrarily; as, to read backwards.()We might have . . . beat them backward home. (Shak.)