If you describe something as ~, you are emphasizing that it is extremely unpleasant.
...the ~ horrors of chemical weapons...
...~ crimes.
= appalling
ADJ emphasis
unspeakably
The novel was unspeakably boring.
ADV: usu ADV adj
If you describe something as ~, you are emphasizing that it is extremely unpleasant.
...the ~ horrors of chemical weapons...
...~ crimes.
= appalling
ADJ emphasis
unspeakably
The novel was unspeakably boring.
ADV: usu ADV adj
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012