signal any communication that encodes a message; "signals from the boat suddenly stopped"
signal box a building from which signals are sent to control the movements of railway trains
signal caller the position of the football player in the backfield who directs the offensive play of his team; "quarterback is the most important position on the team"
signal detection the detection that a signal is being received
signal fire a fire set as a signal
signal flag a rectangular piece of fabric used as a signalling device
signal level the amplitude level of the desired signal