any of various types of signal used as a warning by vessels navigating in fog or mist.
Origin of fog signal
First recorded in 1750–60
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for fog signal
For instance, let a fog-signal be placed at or near water level on one side of an island that has a conical elevation.The Galaxy|Various
A “fog-signal” is employed on railways when the ordinary signals are obliterated within working distances.
British Dictionary definitions for fog signal
a signal used to warn railway engine drivers in fog, consisting of a detonator placed on the line
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