sound [2]
adj
1 complete, entire, firm, fit, hale, hale and hearty, healthy, intact, perfect, robust, solid, sturdy, substantial, undamaged, unhurt, unimpaired, uninjured, vigorous, well-constructed, whole
2 correct, fair, just, level-headed, logical, orthodox, proper, prudent, rational, reasonable, reliable, responsible, right, right-thinking, sensible, true, trustworthy, valid, well-founded, well-grounded, wise
3 established, orthodox, proven, recognized, reliable, reputable, safe, secure, solid, solvent, stable, tried-and-true
4 deep, peaceful, unbroken, undisturbed, untroubled
Antonyms
1 ailing, damaged, flimsy, frail, light, shaky, sketchy, superficial, unbalanced, unstable, weak
2 & 3 fallacious, faulty, flawed, incompetent, irrational, irresponsible, specious, unreliable, unsound, unstable
4 broken, fitful, shallow, troubled