un·sound /ˌən-'sau̇nd/ adj: not sound: as
a: not healthy or whole
b: not mentally normal: not wholly sane
c: not firmly made, placed, or fixed
d: not valid or true
an unsound argument
un·sound·ly adv
un·sound·ness n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.