unprecedented
adj. 前所未有的，史无前例的；（大小、数量、程度等）前所未知的，空前的
例句
The mission has been hailed as an unprecedented success.
这次使命已被宣布为一次空前的成功。
《柯林斯英汉双解大词典》
We are now witnessing an unprecedented increase in violent crime.
我们现在看到暴力犯罪空前增多。
《牛津词典》
Such policies would require unprecedented cooperation between nations.
这样的一些政策会要求国与国之间前所未有的合作。
