Both verbs seem to mean the same thing: "to give support to someone or something". Is there any difference between the verbs?

Also, are there any cases which I can't use "to back (up)" instead of "to support"?

1 Answer 1


To "back" someone or something means to support it.

She backed the ban on WMD.

To "back up" means to be available to substitute for someone or something.

He was backing up our normal delivery man who was out on medical leave.

  • 2
    Sorry, but according to the Cambridge dictionary "to back sb/sth up" means "to provide support for someone or something". dictionary.cambridge.org/ru/… Nov 23, 2016 at 13:28
  • Sounds like you've answered your own question. Good job.
    – EllieK
    Nov 23, 2016 at 13:46
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    If, however, you choose to say, "She backed up the ban on WMD," it won't sound correct.
    – EllieK
    Nov 23, 2016 at 13:53
  • How come I've answered my own question? "to back" means "to give support to someone or something", "to back sth/sb up" - "to provide support for someone or something". Could you please point out the difference, looks like I'm blind. Nov 23, 2016 at 13:57
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    I can't refute the Cambridge Dictionary. I'm merely saying that the two phrases mean different things, Cambridge not withstanding. "Who backs you?" Means who supports your cause or efforts. "Who backs you up?" or "Who is your backup?" Means who will fill in for you when you're absent. Mirriam Webster Backup 1.a.
    – EllieK
    Nov 23, 2016 at 15:39

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