pilot lamp

noun
1.
an electric lamp, used in association with a control, which by means of position or color indicates the functioning of the control; an indicator light or a control light.
Also called pilot light.
Origin
1880-85
Examples from the web for pilot lamp
  • There must be a red pilot lamp which must go on when the respective amber or red systems are activated.
  • Status indication shall be provided for all smoke control equipment, annunciated by fan and zone, by pilot lamp type indicators.
  • There must be a pilot lamp which goes on when the respective amber or red system is activated.
British Dictionary definitions for pilot lamp

pilot lamp

noun
1.
a small light in an electric circuit or device that lights up when the circuit is closed or when certain conditions prevail