n.[C]

1. 指示者；指示物[+that]
   The foreign minister's visit can be taken as one more indicator that the relationships between the two countries are improving.

   外长的访问可以被看作是又一个信号，说明两国关系在改善。

2. （仪器上的）指针，指示器；（车辆上的）变向指示灯
3. 【机】压力计；示功器
4. 【化】指示剂
5. 【生】（说明环境状况的）指示生物（群落）
6. 指标

n.

1. a thing that indicates a state or level.
2. a gauge or meter of a specified kind.
3. Brit. a flashing light on a vehicle to show that it is about to change lanes or turn.
4. Brit. an information board or screen in a railway station, airport, etc.
5. Chemistry  a compound which changes colour at a specific pH value or in the presence of a particular substance, and can be used to monitor a chemical change.