Meaning of INDICATOR in English

INDICATOR

n.1 a person or thing that indicates.

2 a device indicating the condition of a machine etc.

3 a recording instrument attached to an apparatus etc.

4 a board in a railway station etc. giving current information.

5 a device (esp. a flashing light) on a vehicle to show that it is about to change direction.

6 a substance which changes colour at a given stage in a chemical reaction.

7 Physics & Med. a radioactive tracer.

Oxford English vocab.      Оксфордский английский словарь.