stool pigeon

美 
英 
  • n.内线
  • 网络密探;诱捕用的鸽子;卧底,线人
复数:stool pigeons  
stool pigeon
n.
1.
(向警察提供情报的)线人,内线a person, especially a criminal, who helps the police to catch another criminal, for example by spending time with them and getting secret information