Peter Ki asks:
What is the difference between ‘can not’ and ‘cannot’?
Although my personal Error Alarm buzzes whenever I see cannot written as two words, both forms are acceptable usage.
Merriam-Webster lists cannot as one word. If you try looking up “can not” in the online unabridged, you will be sent to a list of suggestions headed by cannot.
According to the entry in the OED, cannot is
the ordinary modern way of writing can not
The historical illustrations given for the negative in the OED shows cannot, can not, and even canot, as well as the contraction can’t:
?a1400 Cursor M. (add. to Cott.) p. 959. 105 And ￼ou ￼at he deed fore cannot sorus be. 1451 Paston Lett. 140 I. 186 Other tydyngs as yett can I non tell you. Ibid. 172 I. 229 Whethir it be thus or non I can not say. 15.. Plumpton Corr. 72, I canot get my money. 1706 Col. Records Penn. II. 256 The House cant agree to this. 1741 RICHARDSON Pamela I. 56 If he..as you say can’t help it. 1742 YOUNG Nt. Th. I. 89 An angel’s arm can’t snatch me from the grave; Legions of angels can’t confine me there. 1827 KEBLE Chr. Y. 4 Without Thee I cannot live. Mod. Can’t you go?
The experts at AskOxford seem to prefer cannot:
Both cannot and can not are acceptable spellings, but the first is much more usual. You would use can not when the ‘not’ forms part of another construction such as ‘not only.’
These two spellings [cannot/can not] are largely interchangeable, but by far the most common is “cannot” and you should probably use it except when you want to be emphatic: “No, you can not wash the dog in the Maytag.”
There’s no difference in meaning between cannot and can not.