What would you consider too much money to have? ∞

How much of it would you like to share? 0

What is 1.0 divided by 0.0? NaN (Not a Number)

What is your middle name? N/A (Not Applicable)

When are you going to retire? TBD (To Be Determined)

When is the next Game of Thrones going to air? TBA (To Be Announced)

What are you going to do, option A or option B? C

In Mathematics and in English, particularly in the age of fill-in-the-blank forms, there are special answers that reject a questions assumptions. Do these answers have a collective name that could be used like so:

"If a question doesn't have an answer put a ___"

  • 1
    Douglas Hofstadter, in Godel, Escher, Bach (popularly known as GEB) appropriated the term Mu from Japanese to mean "I unask that question". It's been used semi-seriously by the geekier types in that sense since then. Some programming languages (e.g. Perl6) even use the name Mu for "the most undefined of objects".
    – Dan Bron
    Commented Jan 5, 2018 at 20:07
  • Doesn't it make more sense to apply the attribute to the question? Personally, I used to transcribe Richard III into all useless blank spaces on forms. I kept a bookmarked copy with me. I got through the entire play once and had started over again before I misplaced the little book. I even did this on job applications, which got me some laughs in interviews. I used to work with government contracts, so I spent a lot of time with forms.
    – Phil Sweet
    Commented Jan 5, 2018 at 20:45
  • On older opinion surveys, a line was set aside for the person conducting the survey to mark an answer as "Don't Know/Other," meaning, presumably that the respondent said he or she didn't know the answer or gave some other answer not included among the automatically tabulated options. Some government forms such as those for voting registration in parts of the United States include an option for "Decline to State," to deal with situations where the person filling in the form would otherwise either leave a line on the form blank or explicitly reject a particular question.
    – Sven Yargs
    Commented Jan 5, 2018 at 22:20
  • SATSQ - Snappy Answer To a Stupid Question leedberg.com/mad/satsq/satsq.html
    – Nigel J
    Commented Jan 5, 2018 at 22:37
  • @DanBron Your comment is the best response so far. Any chance you can develop it into an answer? Commented Jan 6, 2018 at 3:18

5 Answers 5


"Not applicable" seems to be the most general term for this, but it doesn't handle all the cases. If the question is applicable, but just can't be answered yet, "TBD" is common. And in multiple-choice questions, "None of the above" can be offered as a choice.

I don't think there's one, overarching term that encompasses all of these ways to give non-specific answers to questions.


How about 'invalid'?

As in, "If a question doesn't have an answer put an invalid."


Consider calling it an out of band value, borrowing from software terminology:

out-of-band adj 1. In software, describes values of a function which are not in its ‘natural’ range of return values, but are rather signals that some kind of exception has occurred. - The Jargon File

Your sentence would then be:

  • If a question doesn't have an answer[, write] a[n] out of band value.

Consider rejecting the premise of this question and call them explanations (or explanatory placeholders).

explanation noun 1.1 A reason or justification given for an action or belief. - ODO

I'd consider your first two examples to provide straightforward, in-band answers. The remainder implicitly say "no answer" and explicitly provide (an abbreviation for) an answer.

Your sentence would then be:

  • If a question doesn't have an answer[, write] a[n] explanation.

In Mathematics, there is a term called indeterminate expression.

"A mathematical expression can also be said to be indeterminate if it is not definitively or precisely determined." (Wolfram MathWorld)

I think this would be the closest existing term that you could use to describe the English acronymous phrases you've listed.

  • Can you use this to fill in the blank in his question?
    – Barmar
    Commented Jan 5, 2018 at 21:56
  • If a question doesn't have an answer put an indeterminate expression. Commented Jan 5, 2018 at 22:06

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