back up

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back up (third-person singular simple present backs up, present participle backing up, simple past and past participle backed up)

1. (idiomatic, intransitive) To move backwards, especially for a vehicle to do so.

   Coordinate terms: back away, back off, stand back

   That beeping sound indicates that the truck is backing up.

   • 1897 December (indicated as 1898), Winston Churchill, chapter V, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC:

     We expressed our readiness, and in ten minutes were in the station wagon, rolling rapidly down the long drive, for it was then after nine. […] As we reached the lodge we heard the whistle, and we backed up against one side of the platform as the train pulled up at the other.

2. (idiomatic, transitive) To move a vehicle backwards.

   Synonym: reverse

   Hyponym: back out

   Back up the car a little, you're blocking the driveway.

3. (idiomatic, intransitive) To undo one's actions.

   Synonym: back out

   I couldn't see how to finish the project, so I backed up and tried it another way.

4. (idiomatic, intransitive) To reconsider one's thoughts.

   This isn't working. Let's back up and think about it.

5. (idiomatic, computing, transitive) To copy (data) so that it can be restored if the main copy is lost.

   Back up your documents folder before applying the update.

6. (idiomatic, transitive) To provide support or the promise of support to.

   Synonyms: back, support

   You should be careful. This guy is backed up by the local gang.

   When he said I wasn't there, I told him I was, and my buddy backed me up.

   • 2017, BioWare, Mass Effect: Andromeda (Science Fiction), Redwood City: Electronic Arts, →OCLC, PC, scene: Update on Jaal:

     Thank you for backing me up. I know it's not easy delivering bad news-especially to a friend-but sometimes it's the only way we can move forward and begin to heal.

   • 2020 May 6, Tim Dunn, “The Architecture The Railways Built”, in Rail, page 76:

     Researching and corroborating facts to put in my script is one thing, but getting sources to back up the assertions of interviewed contributors can be quite another.

7. (idiomatic, intransitive, cricket) For the non-striker to take a few steps down the pitch, in preparation to taking a run, just as the bowler bowls the ball.
8. (idiomatic, intransitive, cricket) For a fielder to position himself behind the wicket (relative to a team-mate who is throwing the ball at the wicket) so as to stop the ball, and prevent overthrows.
9. (idiomatic, intransitive, of a blockage) To halt the flow or movement of something.

   Synonym: plug up

   When I flushed the toilet, the plumbing backed up and burst.

10. (idiomatic, intransitive, informal) To fill up because of a backlog.

    Synonym: fall behind

    • 1995, "Oubliette" (episode of The X-Files TV series)

      WAITRESS: Hurry up with those drinks, Lucy. We're backing up. (Grabs the drinks LUCY has poured.) What are you doing? These are regular. They all ordered large.

• backupable

• back down
• back into
• back off
• back out

• upback