1. A number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time
   "Economists use indicator numbers to track changes in the cost of living";
   - index, index number, indicant
    
2. A device for showing the operating condition of some system
   "The fuel indicator on the dashboard showed that the tank was nearly empty"
    
3. A signal for attracting attention
   "The flashing light was an indicator of an incoming message"
    
4. (chemistry) a substance that changes colour to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
   "Litmus paper is a common pH indicator used in chemistry labs"
    
5. [Brit] A blinking light on a motor vehicle that indicates the direction in which the vehicle is about to turn
   "He forgot to use his turn indicator before changing lanes";
   - blinker, turn signal [N. Amer], turn indicator, trafficator [Brit]

Derived forms: indicators

Type of: color [US], coloring material [US], colour [Brit, Cdn], colouring material [Brit, Cdn], device, fact, sign, signal, signaling [N. Amer], signalling [Brit, Cdn], visual signal

Part of: electrical system

Encyclopedia: Indicator