stool pigeon

noun

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

1. Watch out for John; I'm sure he's a stool pigeon for the police.
   提防着约翰，我敢肯定他是警方的眼线。
2. I was accused of lacking patriotism and even of being a "Western stool pigeon".
   人们指责我缺乏爱国精神，甚至是“西方的卧底”。
3. Was he a stool pigeon?
   他是来诱供的？
4. Even did six months for assault for beating up some stool pigeon.
   甚至还为袭击某个密探做过六个月牢。
5. As a lawyer, how could you believe a stool pigeon?
   做为一个律师，你怎么能相信一个假证人的话呢？

noun

1. a dummy pigeon used to decoy others

2. someone acting as an informer or decoy for the police

   Synonym:    finksnitchsnitcherstoolpigeonstooliesneaksneakercanary