Unthinkable may mean two different things:

  1. Something that we cannot think about, normally for moral reasons, e.g. killing someone.
  2. Something we cannot think about, because cognitively we are not capable of that.

I want a word to clearly refer to the second, without ambiguously referring to the former, which is the usual meaning (because the second is relatively unthinkable).

Extra details:

"Truly unthinkable" is contradictory, in the sense that you cannot answer what is "truly unthinkable" for you. If you could, it would not be "truly unthinkable", because you can think about it at least to answer.

However, we can think of many things that are truly unthinkable for a dog, corporate strategy may be one of them.

Colors are not completely unthinkable for someone born blind, and music is not truly unthinkable for someone born deaf, both could learn about those things just like Mary the super-scientist.

Scrivener and caveman levels of unthinkable:

  • If we travel in time and we explain to a scrivener that we can store millions of books in our smartphone, the way the smartphone works may be unthinkable or inconceivable to him, but he can understand what we are explaining by showing the smartphone.
  • However, if we try to explain the same to a caveman, then it will be truly unthinkable and truly inconceivable because he does not know what a book is. Even showing a book would not help to understand what a book is, without knowing what the written language is (which is what is stored in the smartphone, not the physical book with pages made of paper).

The difference is that the scrivener may be impressed. Storing books like that is unthinkable, but clearly valuable. The caveman would consider us crazy, you cannot eat the books in the smartphone, and the actual books do not even taste good. The caveman may understand that you put big things into small things (which is not entirely true), but all those things are meaningless for him.

I am searching for a word that would apply to the caveman but not to the scrivener.

Example sentence: The smartphone was incomprehensible for the scrivener; he watched it in awe, estimating what kind of human labor could create such a miraculous wonder, painstakingly taking years to write each book. For the caveman, the device was incomprehensible, and therefore as meaningless and irrelevant as it would be for a snail.

Another: For me, quantum physics is unthinkable, I would have never figured out the wave-particle duality, not in a thousand years. However, the universe before time existed is unthinkable, I cannot think of precedence without time.

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    A former question may help, but be aware that it seems incomprehensible, ironically.
    – Trylks
    Commented Aug 22, 2022 at 18:28
  • Please consider editing the earlier post, otherwise please delete it. Commented Aug 22, 2022 at 18:38
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    I answered this question, but please note that a single word request is expected to include a sample sentence in which that word could be used. Commented Aug 22, 2022 at 21:02
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    I thought that I understood the distinction that you were making between scrivener and caveman based on the two bullet points, but now you've added a couple of paragraphs that are confusing me. You say "I am searching for a word that would apply to the caveman but not to the scrivener", but then you give examples of two words ("incomprehensible" and "unthinkable") that are used in the same way for both of them. There seems to be a contradiction. Commented Aug 23, 2022 at 22:20
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    You may be dealing with an issue of philosophy or logic more than English. All of these words mean that something can't be thought of. The English issue is whether they are being used literally (e.g., "a square circle is unthinkable") or figuratively (e.g., "a Canadian invasion of the United States is unthinkable"). The philosophical / logical issue concerns what it means to be able to "think" of something; a 19th century scrivener can't think of a Kindle in one sense (because he doesn't know what a Kindle is), but in another sense he can (because a time traveller could explain it to him). Commented Aug 23, 2022 at 23:35

7 Answers 7


Incogitable. Its dictionary meaning is similar to other words of the same ilk such as unimaginable,inconceivable. However in usage, it almost always means your second meaning (Something we cannot think about, because cognitively we are not capable of that).

Example sentences from https://www.dictionary.com

  • But this learned writer does not mention how we are to know when anything is ‘absolutely incogitable.’ History of Civilization in England, Vol. 1 of 3|Henry Thomas Buckle

  • The more incogitable a thing becomes, the more ignorant of it do we become—that is the natural supposition. James Frederick Ferrier|Elizabeth Sanderson Haldane

  • What falls out of consciousness becomes incogitable; it lapses, not into nothing, but into what is contradictory. James Frederick Ferrier|Elizabeth Sanderson Haldane

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    This is exactly what I needed, thanks a lot!
    – Trylks
    Commented Sep 12, 2022 at 12:23
  • You are welcome.
    – banuyayi
    Commented Sep 16, 2022 at 17:01

Besides "unthinkable", the most obvious choices are "unimaginable" and "inconceivable". However, all of those words might be used figuratively. (E.g.: "It's unimaginable that Canada would invade the United States.") I think that the word "incomprehensible" is less likely to be used figuratively and therefore may be what you want:

The idea that an electronic device can hold books would be incomprehensible to a caveman.
Corporate strategy is incomprehensible to a dog.

  • These suggestions all fit the caveman and the dog examples, but it is questionable whether they satisfy the OP's requirement that the word not be applicable to the example of the scrivener. It seems that we could say that it would be unimaginable/incomprehensible/inconceivable to somebody from several centuries ago that a multitude of books could be stored in a small, lightweight gadget.
    – jsw29
    Commented Aug 23, 2022 at 21:28
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    @jsw29 I agree that it's questionable; I was only trying to suggest that "incomprehensible" probably works better than the other words. None of them unambiguously satisfies OP's requirement. It doesn't help that OP has now added a paragraph that uses "incomprehensible" for both scrivener and caveman, which I think muddies the question even more. I'll add a comment to try to get some more clarity. Commented Aug 23, 2022 at 22:22

“Beyond our conception

…would seem to be the idea the poster is trying to express. A phrase, but so is “truly unthinkable” (although very silly because it would be unthinkable to write “untruly unthinkable”, I think.)

  • Well, yes but actually no. It is similar to known unknowns and unknown unknowns. So it is like thinkable unthinkable and unthinkable unthinkable. Which on second reading is silly, but there has to be a better way to say it.
    – Trylks
    Commented Aug 22, 2022 at 23:39
  • @Trylks — Nice try, but there’s no similarity. Here “truly” is being used as an intensifier instead of the simpler neutral “most”. But the point is that “unthinkable” is an absolute concept that neither needs or allows an intensifier. Shades of “slightly pregnant”.
    – David
    Commented Aug 23, 2022 at 8:00
  • Well, morally unthinkable and cognitively unthinkable are different. People may be confused by unthinkable or incomprehensible ideas, but they would not be confused by supraliminal ideas, which cannot be perceived to cause confusion. There are clear distinctions between groups of ideas; the words to describe them are not so clear, in my opinion.
    – Trylks
    Commented Aug 23, 2022 at 11:36
  • @Trylks — I think the confusion is caused by non-native speakers who draw wrong conclusions about the meaning/usage of words from a simplistic analysis of their components. The meaning of “unthinkable” is unambiguous to native speakers. There have been several suggestions for English words or phrases to express the idea you appear to have in mind. You would be well advised to drop “truly” because it is not essential to your question and creates — in my mind at least — the impression of someone who does not choose his words with sufficient care.
    – David
    Commented Aug 23, 2022 at 19:08
  • I agree, that is why I am asking. I like "utterly incomprehensible". The previous title could be better: "How to describe something too far away from comprehension to cause confusion?" "Unthinkable" is not an absolute concept as you mention, though. The word has no use as an absolute concept because we cannot think of (absolutely) unthinkable ideas to regularly use the word with that meaning (except, perhaps, in cosmic horror).
    – Trylks
    Commented Aug 23, 2022 at 22:23

I think you're talking about the distinction between whether something is "readily comprehensible" or "utterly incomprehensible" to a sentient, thinking being even if that subject matter, concept, or idea was not previously never known to the interlocutor.

Although the scrivener doesn't know exactly how the phone works, the utility of the phone is readily comprehensible to him even though he doesn't have the proper frame of reference to completely comprehend all the things a phone can do and is.

Whereas the caveman isn't readily going to comprehend the concept of a phone because there are so many other concepts and ideas he must also understand to make sense of it. This reminds me of the psychological concept of "schemas", or how we use our general knowledge that we already know to process stimuli/information in our environment that our brain use make sense of unfamiliar concepts or ideas like you're saying. So, although the button on the side of a phone I've never seen before is a different size than I've ever seen, I still know that generally that type of side button in my experience might control the volume by pressing it up or down if someone put a gun to my head and I HAD to guess.

But of course "understanding" is relative.

I'd personally say that the concept of a phone to a caveman is not readily comprehensible to him (i.e. ain't nobody got time to take the time to explain language, electricity, etc. but maybe just maybe if we took the time to that caveman he could understand it all one day after a lot of explaining and teaching), whereas with your example with the dog the subject matter would be "utterly incomprehensible" for Fido because there's no amount of time or teaching you could put in to teach a dog what the color blue is (because that dog doesn't have the necessary rods and cones to even see colors like us!)

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    You seem to be discussing the example rather than providing an answer to the question. Commented Aug 22, 2022 at 20:09
  • I'm liking this answer. “Utterly inconceivable” seems a better wording than “truly unthinkable.” An alternative wording may be “supraliminal,” but I don't know if that helps or confuses further.
    – Trylks
    Commented Aug 22, 2022 at 23:53

Paralogical. This is a made up word with a plausible reading of “beyond the logical”.


There are plenty of words that in theory have the meaning of “truly unthinkable”, such as supernatural and paranormal, but these have become associated over time with observable phenomena that we can obviously think about and describe (reasonably) in stories. In contrast, something paralogical is something that we cannot reason about at all.

Not surprisingly, it has a definition in psychology:


To use the OP’s examples: For a caveman, a mobile phone would be paralogical. For a scrivener, it would be logical, but “like magic”. Its purpose could be grasped even if its inner workings could not be.

  • New words are great, when necessary. Supraliminal and superlogical seem to imply beyond understanding better than paralogical, which sounds more like an alternative perspective of similar extension. The “mental universe” of the caveman may be richer in details, and even more complex, but also smaller, IMHO.
    – Trylks
    Commented Aug 23, 2022 at 7:05
  • PD: I just realized, perhaps it should be ultralogical, hyperliminal, or something similar.
    – Trylks
    Commented Aug 23, 2022 at 22:39

There is no word that will be immediately (i.e. without an explicit explanation) understood to have precisely the meaning you intend. If you are writing an article in which this concept needs to be used repeatedly, and the distinctions you present are important, you have to simply choose which of the relevant words you will use in which way, and then define them stipulatively, by saying, early in the article, something like:

In this article, I will use inconceivable for . . . and unimaginable for . . . .

Incidentally, you seem to assume that the difference between the scrivener example and the caveman example is a difference in kind (and that that's why we need different terms for them); some people may see them as different only in degree (and therefore see no need for the term that you are asking about).


Unthinkable may mean two different things:

  1. Something that we cannot think about, normally for moral reasons, e.g. killing someone.

2. Something we cannot think about, because cognitively we are not capable of that.

You have not said where you found the definitions, nor have you given any examples of their published use.

You have limited 1. to morality and this is wrong:


unthinkable: Too great, numerous, etc., to be conceived or apprehended by thought; unimaginable.

1897 Westm. Gaz. 6 July 2/1 You wander..in cool glades of unthinkable beauty.

For 2. you need inconceivable or unimaginable. This use of "unthinkable" is archaic:

OED (This entry has not yet been fully updated (first published 1926;)):

2. Incapable of being framed or grasped by thought; incogitable.

?1536 tr. Erasmus Serm. Chylde Jesus i. sig. A.iiii Jesus, which, by an unspeakable, nay with an unthinkable reason, is borne god of god.

1884 H. Spencer in Contemp. Rev. July 33 From whatever point of view we consider it, Bentham's proposition proves to be unthinkable.

  • If I explain something inconceivable or unimaginable to a person, would the person have a reaction to my explanation? Normally we would expect that, perhaps even outrage. I am trying to find a word to refer to something that would fly straight above their heads, and cause absolutely no reaction, it would be "that-word" for them (not baffling, not perplexing,...). The only two possible results are "no effect" or "misunderstanding" (the idea goes above their heads, and they map my words to a different idea).
    – Trylks
    Commented Aug 23, 2022 at 22:55
  • @Trylks If I explain something inconceivable or unimaginable to a person, ...? If you do that, then what you explained is not inconceivable or unimaginable, is it?
    – Greybeard
    Commented Aug 24, 2022 at 8:54
  • For me, no. For the other person, yes.
    – Trylks
    Commented Aug 24, 2022 at 9:09
  • @Trylks If someone can conceive of the idea or imagine it, then it is not inconceivable or unimaginable. If you wish to limit the meaning by adding adjuncts such as "for you/him", then you are moving away from your question (the colour that does not exist in the human spectrum of perception) and you need to rephrase it.)
    – Greybeard
    Commented Aug 24, 2022 at 9:19
  • If we consider that ("If someone can conceive of the idea or imagine it, then it is not inconceivable or unimaginable"), then we cannot use those words whatsoever, nobody can ever mention an inconceivable or unimaginable idea. That is not how language works.
    – Trylks
    Commented Aug 24, 2022 at 9:26

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