What's the difference between "cannot" and "can not?"

Don't they mean the same? It's kind of crazy if they don't.

We learned all about it in 6th grade, but you know how that goes: in one ear and out the other.

  • 4
    Yes, there can be a difference, especially w.r.t. scope of negation and emphasis.
    – F.E.
    Commented Oct 22, 2014 at 23:21
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    – tchrist
    Commented Oct 23, 2014 at 4:05

2 Answers 2


OED-cannot definition: the ordinary modern way of writing can not

Both cannot and can not are acceptable spellings.

There’s no difference in meaning between cannot and can not. but the cannot is much more usual.

Some references from ELU - can't vs cannot

Why is “cannot” spelled as one word?..(a few exceptions)

  • This doesn't seem right. "The variable cannot be initialized" --> it's a pretty useless variable. But, "The variable can not be initialized" --> it is possible for the variable to be in a non-initialized state. So, "cannot" means something (denoted S) is impossible, while "can not" means the inverse of that something (denoted !S) is possible. These two statements do not imply each other. Of course, the second statement could be rendered much more clearly as "The variable can be not initialized," by moving the "not" next to the word being negated. Commented Nov 23, 2023 at 4:18

They do mean the same thing, but common usage over time has made one form more "usual" than the other (namely cannot). It's similar to contractions (can't, don't, won't), except it seems acceptable to use cannot in a formal setting whereas contractions are frowned upon.

Source: http://www.dailywritingtips.com/cannot-or-can-not/

  • 5
    If cannot = can not, whynot donot = do not, or willnot = will not, funknot = fun knot, etc, etc, whatnot. Commented Oct 22, 2014 at 20:58
  • 5
    You're asking a question about consistency in English, which, sadly, no one has an answer to. Contractions seem to have superseded the need for donot and willnot. I predict that other common usages like "noone" might make it into circulation in the future, though (much like someone and whoever). Commented Oct 22, 2014 at 22:17

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