back up meaning and definition

BACK UP verb

Definition of back up (verb)

1. give moral or psychological support, aid, or courage to
   • "She supported him during the illness"; "Her children always backed her up"
   • synonyms: support
2. move backwards from a certain position
   • "The bully had to back down"
   • synonyms: back down, back off
3. establish as valid or genuine
   • "Can you back up your claims?"
   • synonyms: back
4. make a copy of (a computer file) especially for storage in another place as a security copy
   • "You'd better back up these files!"
5. become or cause to become obstructed
   • "The leaves clog our drains in the Fall"; "The water pipe is backed up"
   • synonyms: choke, choke off, clog, clog up, congest, foul
   • antonym: unclog