Something like 'Optionality' or 'Ordinality'? (It's similar in kind to the words "Arity" and "Cardinality")

Example: "Fred listed the XXXity of each parameter, noting whether it was optional or mandatory"

Follow-up question: What part of speech is this?

  • 4
    Optionality is obviously a noun (you are even using it with a definite article in your example) and is included as such in several dictionaries (Wiktionary, Merriam-Webster, Collins). And in fact some dictionaries have a dedicated entry for the suffix -ity.
    – RegDwigнt
    Apr 4, 2013 at 10:16
  • I see - as in "noun referring to a state or quality"... so there isn't a specific word for this? Apr 4, 2013 at 10:32
  • How about 'Necessity'? Does a thesaurus help?
    – Mitch
    Apr 4, 2013 at 12:00
  • Are looking for a part of speech more refined than 'noun'? You're looking for an abstract concept but there's nothing grammatically special about that.
    – Mitch
    Apr 4, 2013 at 12:03

4 Answers 4


There are a few recently contrived words that try to do this; optionality is indeed used from time to time, and I've seen things like mandatoriness too. But actually there are some more established words that do the same job.

Of course, optional-ness is actually binary - something is either optional or mandatory. Therefore the quality of optionality/optional-ness is actually the same as the quality of mandatory-ness or compulsory-ness, just with the polarity reversed.

All of which is a fairly long winded way for me to get around to saying this:

I think the word you're looking for is the noun, necessity.

  • The problem with 'necessity' is that it doesn't play well in if-statements i.e. if (foo.necessity) doSmth() doesn't look good to me.
    – Roman
    Feb 9, 2015 at 12:06
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    @Roman Necessity is the quality (parameter/variable), not the state/value - for that you might use "necessary", "mandatory" or an antonym such as "optional". Something like if (foo.necessity == 'mandatory') doSmth(); elseif (foo.necessity == 'optional') doSmthElse(); else doNecNotSet(); is what we're talking about here. Necessity doesn't hold true/false values, it holds values like "necessary", "mandatory", "optional" etc. But treating English like a programming language isn't always the best way to go, because it isn't one.
    – Waggers
    Mar 6, 2015 at 14:27
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    I arrived here as I wanted to check if "requirement" would be the right fit. As it's a synonym of "necessity" (with high relevance according to Thesaurus.com), I think it works too. "Requirement" sounds more formal that "Necessity" and I'm using it as a header for a column where the values are "Mandatory" or "Optional".
    – ADTC
    Sep 3, 2015 at 10:59
  • On second thought, condition (where it means a state that must be fulfilled) can also be a good alternative (though not a synonym of necessity or requirement). For example, "What is the condition to be met, with regards to this item?" "The item is mandatory" or "The item is optional".
    – ADTC
    Sep 3, 2015 at 11:10

From here:



The fact of being requisite; necessity, need.


It appears that Ordinality is used in this sense (even though it has a more normal meaning of 'ordering'). Maybe this is verging on jargon.

For example: "Ordinality is a property that indicates whether an entity instance is mandatory"

(from: 'Oracle SQL and Pl/SQL Handbook: A Guide for Data Administrators, Developers')

  • 3
    Naming of database properties isn't always a guide to good English usage. Apr 4, 2013 at 16:55
  • Agreed, but in this case the context happened to be appropriate :) Apr 4, 2013 at 21:50
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    This isnt quite right tho - ordinality expresses a reference to an index of an item in a list of things Jan 29, 2020 at 11:41

Mandatory doesn't really mean that something is not optional. This would explain why there isn't really a word to answer your question. The question has a wrong defintion of mandatory. If it was optional or required then you could say electivity.

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