indicator

noun9

1. •
   A pointer or index that indicates something.

   • The visual indicators are a decided improvement, and have reduced the telephoning by the staff in the signalbox. — 1954
2. •
   Any of many substances, such as litmus, used to indicate the concentration of a substance, or the degree of a reaction.
3. •
   A plant or animal whose presence is indicative of some specific environment.
4. •
   A measure, such as unemployment rate, which can be used to predict economic trends.
5. •
   A meter or gauge.
6. •
   The needle or dial on such a meter.
7. •
   (UK, Australia) A turn signal; each of the flashing lights on each side of a vehicle which indicate a turn is being made to left or right, or a lane change etc.
8. •
   A codeword that marks the use of a specific cryptic device.

   • 'Wild' is an anagram indicator showing that the letters of 'danger' have to be rearranged. — 2011
9. •
   A bird, the honeyguide.