adj. 25B6; adjective
structurally unsound : RICKETY, flimsy, wobbly, unstable, crumbling, damaged, rotten, ramshackle, insubstantial, unsafe, dangerous.
this submission appears unsound : UNTENABLE, flawed, defective, faulty, ill-founded, flimsy, unreliable, questionable, dubious, tenuous, suspect, fallacious, fallible; informal iffy.
of unsound mind : DISORDERED, deranged, disturbed, demented, unstable, unbalanced, unhinged, insane; informal touched.
strong.