unspeakable

释义：“难以名言的”，虽然有的时候可以形容正面的事物。但大多数情况后面跟着的是不幸或难以被常人接受的行为。

例句：
Elizabeth becomes an eyewitness to unspeakable horror, as Josh Powell's house explodes into a roaring inferno.
When she released the balcony railing and hurled herself into the void, she was filled with an unspeakable joy---convinced that at long last, she had found grace.