undecidable
adjective
un·de·cid·able
ˌən-di-ˈsī-də-bəl 
: not capable of being decided : not decidable
… a huge popular audience, most of whom must have been baffled and exasperated by its elaborate and undecidable mystifications.—
David Lodge
David Lodge… deconstruction, which teaches that literature is essentially "undecidable," beyond interpretation …—James Atlas
James AtlasTo be complete such a system must be able to prove that any formula expressible in its language (a mathematical equation, for example, or a statement in symbolic logic) is either true or false; nothing can be undecidable.—George Johnson
George JohnsonExamples of undecidable in a Sentence
Recent Examples on the Web
Cris Moore developed one of the earliest and simplest undecidable physical systems.
—Charlie Wood, Wired News, 6 Apr. 2025
Does an algorithm exist to determine this for every equation, or is the problem undecidable?
—Joseph Howlett, WIRED, 9 Mar. 2025
The Blackest of Boxes A striking example of unknowability came to physics in 1990 when Cris Moore (opens a new tab), then a graduate student at Cornell University, designed an undecidable machine with a single moving part.
—Charlie Wood, Quanta Magazine, 7 Mar. 2025
But these, too, can turn out to be undecidable, since one set of interpreters can ascertain an implicit right to privacy, which is invisible to another—or even an explicit right to private ownership of guns, which has been invisible to every preceding set of interpreters.
—Adam Gopnik, The New Yorker, 26 Nov. 2021
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Charlie Wood, Wired News, 6 Apr. 2025
Does an algorithm exist to determine this for every equation, or is the problem undecidable?
—Joseph Howlett, WIRED, 9 Mar. 2025
The Blackest of Boxes A striking example of unknowability came to physics in 1990 when Cris Moore (opens a new tab), then a graduate student at Cornell University, designed an undecidable machine with a single moving part.
—Charlie Wood, Quanta Magazine, 7 Mar. 2025
But these, too, can turn out to be undecidable, since one set of interpreters can ascertain an implicit right to privacy, which is invisible to another—or even an explicit right to private ownership of guns, which has been invisible to every preceding set of interpreters.
—Adam Gopnik, The New Yorker, 26 Nov. 2021
Cite this Entry
“Undecidable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/undecidable. Accessed 31 Oct. 2025.
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