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

… deconstruction, which teaches that literature is essentially "undecidable," beyond interpretation …

—James Atlas

To 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

undecidability

ˌən-di-ˌsī-də-ˈbi-lə-tē 

noun

Examples of undecidable in a Sentence

Recent Examples on the Web

Among the most important undecidable statements is the continuum hypothesis (CH), proved to be undecidable in the Gödelian sense by Paul Cohen in 1963. —Quanta Magazine, 18 May 2026

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

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

Word History

First Known Use

1640, in the meaning defined above

Rhymes for undecidable

• decidable
• slidable