What is the correct spelling of the word "null-space"?

Merriam-Webster puts it in a hyphenated form "null-space", (link).

Wikipedia (link) and MathWorld (link) both put it in either open or closed form "null space" or "nullspace".

Firefox's built-in spellchecker knows only "null space" and "null-space".

I've seen all three spellings in the existing scientific literature.

What would be the correct spelling according to grammar? Is there any difference if we are talking about AmE or BrE? Or should I just pick one spelling and use it across the whole article?

  • Every generation hyphenates the way it wants to. download.lardlad.com/sounds/season14/bartofwar10.mp3 Commented Aug 17, 2015 at 14:50
  • Grammar doesn't hold sway over spelling. People do. (They actually dictate grammar, too, which is why acceptability changes.) They seem to be divided in their opinions on this compound. As do the 'authorities'. The 'correct spelling' is (a) what the person paying you or marking your coursework likes; (b) what the most authoritative authority other than your boss suggests; (c) your preferred style. In that order. Commented Aug 17, 2015 at 16:25
  • @EdwinAshworth ok, not grammar, orthography (though in my books orthography is a part of grammar). And, luckily, there exist norms that are accepted by an overwhelming majority of language users, which become the "correct" grammar. And linguists fix that norm in rulebooks. Hence, my question: according to current rules of the language, what is the correct spelling? On a side note, not all languages admit such a free interpretation of spelling. Commented Aug 17, 2015 at 20:23
  • 1
    All the spellings are used (as you yourself point out), and in reasonably authoritative articles etc. Linguists don't seem to have 'fixed a norm in rulebooks' here (have you never noticed that dictionaries don't always seem to agree on some spellings?) I've spelt (FF will probably argue for 'spelled', but I'm making a point) out what the principal considerations are, in order. The open form seems the most popular, but none is 'incorrect'. Commented Aug 17, 2015 at 20:41
  • You can also spell it kernel. Commented Aug 19, 2015 at 1:26

1 Answer 1


null space

This is what I have always seen, and I did a quick check on google scholar just now, and verified that this is more common than the other two.

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