Signal, n.
Etymology: [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.
2 other Webster entries under this spelling
Signal, a.
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.
Signal, 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.
Shades of meaning
Fernald has no entry of its own for signal; he lists it under sign.
Where he writes about it:
While a sign may be involuntary, and even unconscious, a signal is always voluntary, and is usually concerted; a ship may show signs of distress to the casual observer, but signals of distress are a distinct appeal for aid. — from sign