眼线 (yǎn xiàn) — informer, scout; (colloquial) spy, enemy observer

Definition

Examples

• 他给警察当眼线，提供了很多情报。
  Tā gěi jǐng chá dāng yǎn xiàn, tí gōng le hěn duō qíng bào.
  He worked as an informant for the police and provided a lot of intelligence.
• 警方在犯罪集团内部安插了眼线。
  Jǐng fāng zài fàn zuì jí tuán nèi bù ān chā le yǎn xiàn.
  The police planted an informer inside the criminal organization.
• 他是一名敌后工作的眼线。
  Tā shì yì míng dí hòu gōng zuò de yǎn xiàn.
  He is an informant working behind enemy lines.