signal - noun

any nonverbal action or gesture that encodes a message

any incitement to action

an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes

signal - verb

• communicate silently and non-verbally by signals or signs
• be a signal for or a symptom of

signal - adjective

• notably out of the ordinary

signal - thesaurus

bespeak   betoken   indicate   point   sign   signaling   signalise   signalize