Signal

A sign made for the purpose of giving notice to a person of some occurence, command, or danger; also, a sign, event, or watchword, which has been agreed upon as the occasion of concerted action.

A token; an indication; a foreshadowing; a sign.

Noticeable; distinguished from what is ordinary; eminent; remarkable; memorable; as, a signal exploit; a signal service; a signal act of benevolence.

Of or pertaining to signals, or the use of signals in conveying information; as, a signal flag or officer.

To communicate by signals; as, to signal orders.

To notify by a signals; to make a signal or signals to; as, to signal a fleet to anchor.

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

any nonverbal action or gesture that encodes a message; "signals from the boat suddenly stopped"