signal definition

1. any nonverbal action or gesture that encodes a message
• examples: signals from the boat suddenly stopped
2. any incitement to action
• examples: he awaited the signal to start
• examples: the victory was a signal for wild celebration
3. an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
4. notably out of the ordinary
• examples: the year saw one signal triumph for the Labour party