Signal word meaning and definition

[noun] any communication that encodes a message; "signals from the boat suddenly stopped"
[noun] any incitement to action; "he awaited the signal to start"; "the victory was a signal for wild celebration"
[noun] an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
[adjective] notably out of the ordinary; "the year saw one signal triumph for the Labour party"
[verb] be a signal for or a symptom of; "These symptoms indicate a serious illness"; "Her behavior points to a severe neurosis"; "The economic indicators signal that the euro is undervalued"
[verb] communicate silently and non-verbally by signals or signs; "He signed his disapproval with a dismissive hand gesture"; "The diner signaled the waiters to bring the menu"

\Sig"nal\, n. [F., fr. LL. signale, fr. L. signum. See {Sign}, n.] 1. 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. All obeyed The wonted signal and superior voice Of this great potentate. --Milton. 2. A token; an indication; a foreshadowing; a sign. The weary sun . . . Gives signal of a goodly day to-morrow. --Shak. There was not the least signal of the calamity to be seen. --De Foc.
\Sig"nal\, a. [From signal, n.: cf. F. signal['e].] 1. Noticeable; distinguished from what is ordinary; eminent; remarkable; memorable; as, a signal exploit; a signal service; a signal act of benevolence. As signal now in low, dejected state As erst in highest, behold him where he lies. --Milton. 2. Of or pertaining to signals, or the use of signals in conveying information; as, a signal flag or officer. {The signal service}, a bureau of the government (in the United States connected with the War Department) organized to collect from the whole country simultaneous raports of local meteorological conditions, upon comparison of which at the central office, predictions concerning the weather are telegraphed to various sections, where they are made known by signals publicly displayed. {Signal station}, the place where a signal is displayed; specifically, an observation office of the signal service. Syn: Eminent; remarkable; memorable; extraordinary; notable; conspicuous.
\Sig"nal\, v. t. [imp. & p. p. {Signaled or Signalled}; p. pr. & vb. n. {Signaling} or {Signalling}.] 1. To communicate by signals; as, to signal orders. 2. To notify by a signals; to make a signal or signals to; as, to signal a fleet to anchor. --M. Arnold.

Morse code: ... .. --. -. .- .-..