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.

Origin of pilot lamp

First recorded in 1880–85
Also called pilot light.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012