decidability|dɪsaɪdəˈbɪlɪtɪ| [f. decidable a. + -ity, tr. G. entscheidbarkeit.] The quality of being decidable (see next). 1940in W. V. Quine Math. Logic 344. 1959 K. R. Popper Logic of Sci.Disc. viii. 191 The questions I have raised..constitute the problem of decidability.