inexcusable
🇺🇸
/ˌɪnɪkˈskjuːzəbl/
🇬🇧
/ˌɪnɪkˈskjuːzəbl/
so bad that it cannot be accepted or forgiven
Not apologizing for such a big mistake is inexcusable.
为这么大的错误不道歉是不可原谅的。