adj. 1. (Logic) also called sound. a. (of a set of statements) capable of all being true at the same time in the same circumstances or under the same interpretation.
b. (of a formal system) not enabling the deduction of a contradiction from the axioms, or, more generally, not having an atomic sentence as a theorem. Compare complete (sense 4).
2a. (of a congruence or equation) possessing a solution.
b. more generally, (of a system of relations or equations, particularly a linear system) able to be simultaneously satisfied; possessing a solution. 3. (Statistics) (of a sequence of tests) such that, as the sample size increases, the probability of accepting a fixed alternative hypothesis when it is true tends to unity.