back up

present singular third person backs up · participle present backing up · participle past backed up · past backed up

1. idiomaticintransitiveTo move backwards, especially for a vehicle to do so.

   That beeping sound indicates that the truck is backing up.

   1 more example

   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.

   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

2. idiomatictransitiveTo move a vehicle backwards.

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

   Synonyms: reverse

3. idiomaticintransitiveTo undo one's actions.

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

   Synonyms: back out

4. idiomaticintransitiveTo reconsider one's thoughts.

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

5. idiomatictransitivecomputingTo copy (data) so that it can be restored if the main copy is lost.

   Back up your documents folder before applying the update.

6. idiomatictransitiveTo provide support or the promise of support to.

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

   5 more examples

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

   "All the same, governor, what he says is right," put in the other, anxious to back up his friend now that the first step had been taken.

   1934, Ernest Bramah [pseudonym; Ernest Brammah Smith], The Bravo of London

   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.

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

   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.

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

   It turns out, there’s research that backs up the usefulness of lowering our expectations. Participants in one study had to make decisions that either led to financial gains or losses, all while inside a magnetic resonance imaging (MRI) machine. Researchers then duplicated this experiment as an app to crowdsource more data.

   2024 May 14, Clay Drinko, “Lower Your Expectations”, in Psychology Today

   Synonyms: back, support

7. idiomaticintransitiveball gamesFor 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. idiomaticintransitiveball gamesFor 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. idiomaticintransitiveTo halt the flow or movement of something.

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

   Synonyms: plug up

10. idiomaticinformalintransitiveTo 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.

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

    Synonyms: fall behind

11. obsoletemediaTo run a printing press in reverse.
12. idiomaticintransitiveIf 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.

    Synonyms: abut, border