RhymeZone: back up definitions

Definitions of back up:

verb: make a copy of (a computer file) especially for storage in another place as a security cop
Example: "You'd better back up these files!"
verb: move backwards from a certain position
verb: establish as valid or genuine
Example: "Can you back up your claims?"
verb: give moral or psychological support, aid, or courage to
verb: become or cause to become obstructed