stool pigeon
英 [ˈstuːl pɪdʒɪn]
美 [ˈstuːl pɪdʒɪn]
n. (向警察提供情报的)线人，内线
牛津词典
noun
- （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
英英释义
noun
- a dummy pigeon used to decoy others
- someone acting as an informer or decoy for the police