There are four types of deontic modality, which can be expressed by the following modal expressions:

  1. Can
  2. Need not
  3. Must not
  4. Must

Out of these, 1, 3, and 4 respectively corresponds to the following nouns:

  1. Permission
  2. ???
  3. Prohibition
  4. Obligation

Is there a simple word that corresponds to type 2?

  • 6
    There are actually many more than four types of deontic modality. Every modal auxiliary has at least one, and sometimes more than one deontic sense (can can mean deontic permission or deontic ability). As for the deontic sense of need not, it means Not (Necessary p), just like don't need to or don't have to, and there doesn't appear to be a neat English term to refer to that logical situation. There often isn't; that's why Deontic gets used. Commented Dec 8, 2011 at 19:32
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    Can expresses ability, doesn't it? For permission, the verb is may.
    – Marthaª
    Commented Dec 8, 2011 at 19:42
  • 2
    If you prefer. Of course, preferences differ, and usages even more so. Commented Dec 8, 2011 at 19:50
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    Aren't Can and Need Not the same? Or do you mean Should vs Should Not Commented Dec 8, 2011 at 20:43
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    @ErickRobertson: Plenty, I am sure.
    – Kris
    Commented Dec 9, 2011 at 9:05

6 Answers 6


Remission has a sense of exemption from doing something. So either of the two could serve the purpose.

  • 1
    Awesome. That is the word I was looking for. Remission was not in my vocabulary, but yes, I know the word exemption, and I think that is the perfect fit.
    – sawa
    Commented Dec 9, 2011 at 5:13
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    Remission in this sense is typically found only in legalese. We also see some occurrences in administration documents in the corporate and academic fields. I do not know if it is used as such in general literature or speech, though.
    – Kris
    Commented Dec 9, 2011 at 5:34
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    Can I expect a comment about the down vote, please?
    – Kris
    Commented Dec 9, 2011 at 7:25
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    -1: I wasn't the original downvoter, but remission doesn't mean exemption in any normal context. And as @John comments to OP, there are many "shades" of deontic modality - to me, exemption largely steps outside the entire continuum, rather than indicating the degree to which something "ought to be true". Commented Dec 9, 2011 at 13:23
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    No, but Kris is correct that "remiss" and "remit" do not, in ordinary (or even non-legal formal) usage mean "need not". I don't know about legal usage.
    – Ryan Haber
    Commented Dec 9, 2011 at 15:28

Optionality - noun form for the quality of being Left to choice; not compulsory or automatic.

Apparently this word has become significantly more common over the past 50 years.

  • Chris's answer turned out to be even better to me. Yours is still next best.
    – sawa
    Commented Dec 9, 2011 at 5:11
  • Yeah, and to keep the endings the same (which is nice), use option.
    – Ryan Haber
    Commented Dec 9, 2011 at 15:29
  • @Ryan: Per my comment to Terry's answer, I think option and election would look a bit odd alongside OP's other nouns, because they're both firmly established in somewhat different usages. Commented Dec 9, 2011 at 17:20
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    @FumbleFingers: I agree that election doesn't fit. It has a range of meanings with a shared underlying connection, but its common usage is so strong that to mean it as option is foolish.
    – Ryan Haber
    Commented Dec 9, 2011 at 19:09
  • @FumbleFingers: Option, on the other hand, strikes me as particularly good. The items of a well-formed list should be the same part of speech, at least, so that each item fulfills the same grammatical role. Option satisfies that requirement, and also has the benefit having the same ending, so there is a certain assonance. Finally, it expresses perfectly something that you may, not need not do. "There is permission to sing. There is the option to sing. There is a prohibition on singing. The is an obligation to sing." Perfect!
    – Ryan Haber
    Commented Dec 9, 2011 at 19:12

Unnecessity would fit the bill, if only it weren't obsolete. However, needlessness is not obsolete. To avoid the contrived aura, you may desire to go for a longer phrase and just use absence of necessity or lack of necessity. Or, consider using a positive-oriented word: optionality.

I gave FumbleFingers an upvote on optionality and wanted to point out that it is not only significantly more common than it was fifty years ago, it has even become more common than any of the other options:

On that basis, I think optionality deserves the cake on this issue.

  • It is actually 'absence of necessity', and I am wondering if there is a single word to express that.
    – sawa
    Commented Dec 8, 2011 at 19:04
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    Unless you allow 'needlessness'. Commented Dec 8, 2011 at 19:26
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    Needlessness seems to be a good choice after optionality.
    – sawa
    Commented Dec 8, 2011 at 19:46
  • 'non-necessity' seems fine to me. Commented Dec 9, 2011 at 0:28
  • Wondering: Does needlessness convey a negative overtone like superfluousness ?
    – TaW
    Commented May 16, 2015 at 18:15

When need is used in the positive form it signifies necessity. In the negative form it signifies lack of necessity.

  • 1
    I was wondering if it is possible to say that in a single word. It looks like optionality or needlessness would give that meaning.
    – sawa
    Commented Dec 8, 2011 at 19:47
  • @sawa: I agree. I gave you the term used in grammar books. But I think you chose the correct answer wisely.
    – Irene
    Commented Dec 8, 2011 at 19:53

What about elective?

Elective: not compulsory; optional ; possible but not necessary; left to personal choice

You need to take this course = You are required to take this course (required course)

You needn't take this course = This course is elective to you (elective course)

  • The big problem with this one is when you want a noun form for the quality of being concerned with elective matters. I was a bit iffy about putting up optionality, but it's positively commonplace by comparison with electivity Commented Dec 8, 2011 at 21:19
  • @FumbleFingers Elective could be a noun form itself as in "free electives". What do you think of it?
    – Terry Li
    Commented Dec 8, 2011 at 21:32
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    Yes, I do think it's reasonable to "force" these adjectives into noun roles (you could do the same with optional). It's just they seem a bit out of place when the other three in the list are "natural" nouns formed using the -tion suffix, which we can't do with either of our offerings. Well, you could have election, I suppose, but standard usage for that word makes it a bit awkward. I certainly couldn't get away with option! :) Commented Dec 8, 2011 at 21:42

Other synonyms to consider:

  • noncompulsory
  • nonobligatory / nonobligational
  • discretionary / discretional
  • voluntary

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