Adjective:

1. not discovered;

   "with earth-based telescopes many stars remain undiscovered"
   

2. not yet discovered;

   "undiscovered islands"
   

unknownadj.未知的；不出名的

unexploredadj.未勘查过的；未开拓的

1. At last, the miners struck on an undiscovered gold mine.
   最后，矿工们突然发现了一个不为人知的金矿。
2. I spent most of my time searching for undiscovered treasures.
   我用去我大部分的时间去寻找那未被发现的财宝。