Based on reasonable or adequate grounds; well-founded; justifiable.

Of an argument, proof, piece of evidence, etc.: compelling, cogent, convincing; clear, obvious.

Of reason: sound, well-regulated. Obsolete.

= pregnant, adj.2 Obsolete.

Rhetoric. Of or concerned with the law, legal. Obsolete. rare.

That ‘concludes’ a question or an opponent (see conclude, v. 10 4); conclusive, decisive, convincing.

Of an argument, idea, theory, etc.: cogent, effective, convincing.

Of arguments, reasons, etc.: Having a sound or substantial foundation; based upon sound principles or indisputable facts.

Conclusive, decisive, convincing. Obsolete.

Of arguments, proofs, assertions, etc.: Well founded and fully applicable to the particular matter or circumstances; sound and to the point; against…

Based on good authority; (also) legally acceptable or binding; valid.

Of an argument, statement, etc.: That closes or decides the question; decisive, convincing.

esp. Having power to compel assent or belief; argumentatively forcible, convincing.

Sanctioned by the laws of reasoning; logically admissible or inferable.

Originally and chiefly U.S. (originally Law). Of an argument, point, objection, etc.: aptly or judiciously raised; justifiable; convincing.