I've been looking for a general word to define an idea that seems true, but simply isn't.

A simple example: "The Earth is flat." If all you know is the world outside your window, and you've never done any basic experiments, read books, or seen photos to the contrary, this seems like a reasonable explanation. But it doesn't take too much more examination to find out that it just isn't so.

The key point here is that it's something a reasonable person could reasonably believe.

The closest I've come to what I'm looking for is "verisimilitude." I looked at this answer, but it seems to me that words like "spurious" or "nonsense" seem to imply some ill-intent to deceive, which is not what I'm after. (Or maybe it's more a concept than a word, and that's ok too, if anyone has thoughts on that.)

  • 2
    "Illusory" might be closer...
    – Raydot
    Commented Mar 15, 2021 at 15:31
  • I was about to compose an answer based on illusory, believing it to be the best fit to the question, but I cede to @Dave Kanter.
    – Anton
    Commented Mar 15, 2021 at 16:25
  • 3
    Does this answer your question? What is another word for a false belief or opinion on something that people hold true and repeat because they have heard it repeated so many times? (misbelief, misconception, false impression, fallacy, false notion, old wives' tale, urban myth/legend ... delusion ...). Commented Mar 15, 2021 at 16:35
  • 1
    "Canard" seems to me to imply an intention to deceive. "Misconception" is a good one.
    – Raydot
    Commented Mar 15, 2021 at 18:05
  • 1
    You may just be heading for 'paradox' then: [Merriam-Webster] << paradox ... 2a: a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true >> [Collins] allows the 'is true' subsense: << paradox (1) a seemingly absurd or self-contradictory statement that is or may be true: ...>>. Obviously, if T is true, T' is not true. Commented Mar 16, 2021 at 19:37

2 Answers 2


Seemingly works well for the given context.

appearing to be something, especially when this is not true:

He remains confident and seemingly untroubled by his recent problems.


You could this say: The earth is seemingly flat. (which it isn't in reality.)

  • I like the idea of "seemingly true." That might be it...
    – Raydot
    Commented Mar 15, 2021 at 15:29

I would use ostensibly.

OED : as appears or is stated to be true, though not necessarily so

  • But I suppose in my situation the real truth may not be known.
    – Raydot
    Commented Mar 16, 2021 at 19:07
  • In the context in which I ask the question, the real truth may not be known. Or is not known.
    – Raydot
    Commented May 3, 2021 at 15:05

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