supergrass
英 [ˈsuːpəɡrɑːs]
美 [ˈsuːpərɡræs]
n. (为求得宽大处理)向警方告密的罪犯
复数：supergrasses第三人称单数：supergrasses
牛津词典
noun
- （为求得宽大处理）向警方告密的罪犯
a criminal who informs the police about the activities of a large number of other criminals, usually in order to get a less severe punishment
柯林斯词典
- 向警方告密的人;向警方揭发犯罪团伙的人
A supergrass is a person who gives the police information about a large group of criminals.