indicator

UK: /ˈɪndɪkeɪtə^r/ US: /ˈɪndɪˌkeɪtɚ/ ,(in′di kā′tər)

WordReference Random House Learner's Dictionary of American English © 2025

in•di•ca•tor /ˈɪndɪˌkeɪtɚ/   n. [countable]

1. a person or thing that indicates.
2. Mechanical Engineering a pointing device, as a needle on the dial of a measuring instrument:
   The indicator showed 120 miles an hour.
3. Mechanical Engineering a light on a car that flashes to show which way the car will turn.

WordReference Random House Unabridged Dictionary of American English © 2025

in•di•ca•tor  (in′di kā′tər), n. 

1. a person or thing that indicates.
2. Mechanical Engineering a pointing or directing device, as a pointer on the dial of an instrument to show pressure, temperature, speed, volume, or the like.
3. Mechanical Engineering an instrument that indicates the condition of a machine or the like.
4. Mechanical Engineering an instrument for measuring and recording variations of pressure in the cylinder of an engine.
5. Chemistry
   • a substance, as litmus, that indicates the presence or concentration of a certain constituent.
   • a substance often used in a titration to indicate the point at which the reaction is complete.
6. Ecology a plant or animal that indicates, by its presence in a given area, the existence of certain environmental conditions.

• Medieval Latin indicātor, equivalent. to Latin indicā(re) to indicate + -tor -tor
• 1660–70

Collins Concise English Dictionary © HarperCollins Publishers::

indicator / ˈɪndɪˌkeɪtə/ noun

1. something that provides an indication, esp of trends
   See economic indicator
2. a device to attract attention, such as the pointer of a gauge or a warning lamp
3. an instrument that displays certain operating conditions in a machine, such as a gauge showing temperature, speed, pressure, etc
4. a device that records or registers something, such as the movements of a lift, or that shows information, such as arrival and departure times of trains
5. Also called: blinker a device for indicating that a motor vehicle is about to turn left or right, esp two pairs of lights that flash when operated or a pair of trafficators
6. Also called: dial gauge a delicate measuring instrument used to determine small differences in the height of mechanical components. It consists of a spring-loaded plunger that operates a pointer moving over a circular scale
7. a substance used in titrations to indicate the completion of a chemical reaction, usually by a change of colour
8. Also called: indicator species a plant or animal species that thrives only under particular environmental conditions and therefore indicates these conditions where it is found