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Webster 1913 Edition

Adj.

Capable of being decided; determinable.

Adj.

That may be decided.

See also: décidable

decidable ‎(comparative more decidable, superlative most decidable)

capable of being decided.
(computer science) describing a set for which there exists an algorithm that will determine whether any element is or is not within the set in a finite amount of time.
It is easy to show that the set of even numbers is decidable by creating the relevant Turing machine.
(logic) in intuitionistic logic, a proposition P is decidable in a given theory if it can be proven from the theory that "either P or not P", i.e. in symbols: $P\vee \neg P$ .^[1]

capable of being decided

computer science: describing a set