Founded in truth or right; supported by justice; not to be overthrown on refuted; not fallacious; as, sound argument or reasoning; a sound objection; sound doctrine; sound principles.

a logic is sound with respect to its semantics if only true sentences are derivable under the inference rules from premises which are themselves all true. speculation formation of theories or conjectures, especially without a firm factual basis

An inference is sound just in case it is valid and all of its premises are true.

a deductive argument is sound if and only if it is both valid and has true premises.

reflects weight of sound argument or evidence; "a sound argument"

(1) an argument showing what we should believe but won't; (2) indeterminately produced by falling trees.

an argument is sound if and only if it is valid and contains only true premises.