not sound; unhealthy, diseased, or disordered, as the body or mind.

decayed or impaired, as timber or foods; defective.

not solid or firm, as foundations.

not well-founded or valid; fallacious

an unsound argument.

easily broken; light

unsound slumber.

not financially strong; unreliable

an unsound corporation.

adjective

safe , sound , stable , strong , well

adjective

ailing , crazed , dangerous , decrepit , defective , delicate , demented , deranged , diseased , erroneous , fallacious , false , faulty , flawed , fragile , frail , ill , illogical , inaccurate , incongruous , incorrect , infirm , in poor health , insane , insecure , insubstantial , invalid , lunatic , mad , not solid , rickety , shaky , specious , tottering , unbacked , unbalanced , unhealthy , unhinged , unreliable , unsafe , unstable , unsteady , unsubstantial , unwell , weak , wobbly , feeble , flimsy , puny , weakly , brainsick , crazy , daft , disordered , distraught , dotty , maniac , maniacal , mentally ill , moonstruck , off , touched , wrong , sophistic , spurious , mistaken , untrue , ill-advised , ill-considered , impolitic , imprudent , indiscreet , injudicious , chancy , decayed , foolish , hairy , hazardous , impaired , imperfect , risky , senseless , sick , sophistical , treacherous , unfit , untenable , weakened