(NOT ACCEPTABLE) [adjective] - (esp. of a person's activities) not good enough, acceptable or able to be trustedKilmer, who is serving a life sentence, claims he was convicted on the basis of unsound police evidence.There have been allegations that he approved unsound practices as director of the now-defunct bank.I've always been convinced that the judgement of most film critics is unsound.
UNSOUND
Meaning of UNSOUND in English
Cambridge English vocab. Кембриджский английский словарь. 2012