Definition of unsound adjective from the Oxford Advanced Learner's Dictionary

unsound

adjective

ˌʌnˈsaʊnd

ˌʌnˈsaʊnd

1 not acceptable; not holding acceptable viewsideologically unsoundThe use of disposable products is considered ecologically unsound.2 containing mistakes; that you cannot rely on

Synonym

unreliableThe methods used were unsound.3 (of a building, etc.) in poor condition; weak and likely to fall downThe roof is structurally unsound.

Opposite

soundunsoundness

ˌʌnˈsaʊndnəs unsoundness pronunciation American

ˌʌnˈsaʊndnəs

noun [uncountable]

Idioms

of unsound mind

(law) not responsible for your actions because of a mental illness