indicator

/ˈɪn.dɪ.ˌkeɪ.tə(ɹ)/

#5,774 of the most-used English words

noun

1. A pointer or index that indicates something.
2. A meter or gauge.
3. The needle or dial on such a meter.
4. Any of many substances, such as litmus, used to indicate the concentration of a substance, or the degree of a reaction.

Similar: blinker, directional, directional signal, trafficator, turn indicator, turn signal