back up

verb backs up · backing up · backed up

1. idiomatic, intransitive To move backwards, especially for a vehicle to do so. That beeping sound indicates that the truck is backing up.
2. idiomatic, transitive To move a vehicle backwards. Back up the car a little, you're blocking the driveway.

   Similar: reverse

3. idiomatic, intransitive To undo one's actions. I couldn't see how to finish the project, so I backed up and tried it another way.

   Similar: back out

4. idiomatic, intransitive To reconsider one's thoughts. This isn't working. Let's back up and think about it.
5. idiomatic, 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. You should be careful. This guy is backed up by the local gang.

   Similar: back, support

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

   Similar: plug up

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

    Similar: fall behind

11. obsolete To run a printing press in reverse.
12. idiomatic, intransitive If a property backs up to another property, that means it abuts or shares a border with another property. We bought this house specifically because it backs up to our son's school.

    Similar: abut, border