From Longman Dictionary of Contemporary Englishimpermissibleim‧per‧mis‧si‧ble /ˌɪmpɜːˈmɪsəbəl $ -ɜːr-/ adjective formalLET/ALLOWsomething that is impermissible cannot be allowedOPP permissibleExamples from the Corpusimpermissible• The conduct of the officers in this case was impermissible.• I consider that such doctrine would be dangerous and impermissible.• To switch off the respirator otherwise is impermissible.• Codes of conduct were beginning to emerge and a range of permissible and impermissiblesubjects was being informally drawn up.