Dictionary definition · signal
noun
- any nonverbal action or gesture that encodes a message"signals from the boat suddenly stopped"
- any incitement to action"he awaited the signal to start"
- an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
verb
- communicate silently and non-verbally by signals or signs"He signed his disapproval with a dismissive hand gesture"
- be a signal for or a symptom of"These symptoms indicate a serious illness"
adjective
- notably out of the ordinary"the year saw one signal triumph for the Labour party"
Source: Open English WordNet (CC BY 4.0).