unsound
1 ailing, defective, delicate, deranged, diseased, frail, ill, in poor health, unbalanced, unhealthy, unhinged, unstable, unwell, weak
2 defective, erroneous, fallacious, false, faulty, flawed, ill-founded, illogical, invalid, shaky, specious, unreliable, weak
3 flimsy, insecure, not solid, rickety, shaky, tottering, unreliable, unsafe, unstable, unsteady, wobbly
Antonyms
3 reliable, safe, solid, sound, stable, steady, strong, sturdy, substantial