indicator

Noun

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 November, “Train Arrival Indicators at Euston”, in Railway Magazine, page 738:
   • These old indicators [at Earl's Court station] show the destination of the next train by the appearance of an illuminated arrow next to the station name. The arrow may indicate that a train is going to Wimbledon, but it...
   • The phrase was, and remains, a double-edged sword: a testament to the hard-working and hard-living citizens of the Crescent City and an indicator of the “ah, whatever” shrug hanging over its corrupt politics, its...
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.
5. A plant or animal whose presence is indicative of some specific environment.
6. A measure, such as unemployment rate, which can be used to predict economic trends.
7. 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.

   Synonyms: blinker directional directional signal direction indicator trafficator turn indicator turn signal

8. A bird, the honeyguide.
9. 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 December 9, Collins, Crossword Secrets (Collins Little Book), HarperCollins UK, →ISBN, page 6:
   • We surrounded the strike, Snowy (5) Snowy is the definition in this clue. Ignore the punctuation and capital letter of Snowy! Surrounded is the container indicator. - 2012 October 15, Denise Sutherland, Solving Cryptic...
   • We have already mentioned 'in' having multiple uses; 'round' or 'around' might be a container indicator or a reversal indicator; 'without' might be a container indicator or a deletion indicator, and so on. - 2020 August...