(为求取宽大处理而) 向警方告密的人

The criminal was a supergrass who performed meritorious service to atone his crimes and obtained clemency from the fuzz.

这名罪犯向警方告密，主动赎罪，获得了警方的宽大处理。

优质大麻

The cannabis that is the richest in resin is sometimes called supergrass.

这种脂胶最丰富的大麻被称为优质大麻。