un·sound 
/ˌʌnˈsaʊnd/ adjective
/ˌʌnˈsaʊnd/ adjective [more unsound; most unsound] 1 : not based on truth or logic : not showing good judgment
▪ unsound [=faulty] arguments ▪ unsound business practices 2 : poorly built or in bad condition
▪ an unsound [=unsafe] building ▪ The roof is structurally unsound.
▪ unsound [=faulty] arguments ▪ unsound business practices
▪ an unsound [=unsafe] building ▪ The roof is structurally unsound.
of unsound mind
law : mentally ill : not sane
▪ He was found to be of unsound mind when he committed the murder.
▪ He was found to be of unsound mind when he committed the murder.
