. (Railroads) One of the danger signals or safety signals which guide the movement of trains in a block system. The signal is often so coupled with a switch that act of opening or closing the switch operates the signal also. [ Webster 1913 Suppl. ]

n. a loud low warning sound that can be heard by fog-bound ships; a foghorn.
Syn. -- foghorn. [ WordNet 1.5 ]

. (Meteor.) A signal consisting of a white flag with a black center, used by the United States Weather Bureau to indicate that a local frost is expected. It is used only in Florida and along the coasts of the Pacific and the Gulf Mexico. [ Webster 1913 Suppl. ]

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. [ 1913 Webster ]

All obeyed
The wonted signal and superior voice
Of this great potentate. Milton. [ 1913 Webster ]

2. A token; an indication; a foreshadowing; a sign; anything taken as evidence of some process. [ 1913 Webster +PJC ]

The weary sun . . .
Gives signal of a goodly day to-morrow. Shak. [ 1913 Webster ]

There was not the least signal of the calamity to be seen. De Foc. [ 1913 Webster ]

3. Hence: (Electronics) A measureable electrical quantity, such as voltage or current, that conveys information by varying in magnitude over time; as, the signals from the strongest commercial radio stations can be received over hundreds of miles. [ PJC ]

a. [ From signal, n.: cf. F. signalé. ] 1. Noticeable; distinguished from what is ordinary; eminent; remarkable; memorable; as, a signal exploit; a signal service; a signal act of benevolence. [ 1913 Webster ]

As signal now in low, dejected state
As erst in highest, behold him where he lies. Milton. [ 1913 Webster ]

2. Of or pertaining to signals, or the use of signals in conveying information; as, a signal flag or officer. [ 1913 Webster ]

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. [ 1913 Webster ]

Syn. -- Eminent; remarkable; memorable; extraordinary; notable; conspicuous. [ 1913 Webster ]

v. t. [ imp. & p. p. Signaled i>or Signalled; p. pr. & vb. n. Signaling or Signalling. ] 1. To communicate by signals; as, to signal orders. [ 1913 Webster ]

2. To notify by a signals; to make a signal or signals to; as, to signal a fleet to anchor. M. Arnold. [ 1913 Webster ]

n. One who makes signals; one who communicates intelligence by means of signals. [ 1913 Webster ]

n. The quality or state of being signal or remarkable. [ Obs. ] Sir T. Browne. [ 1913 Webster ]

v. t. [ imp. & p. p. Signalized p. pr. & vb. n. Signalizing ] [ From Signal, a. ] 1. To make signal or eminent; to render distinguished from what is common; to distinguish. [ 1913 Webster ]

It is this passion which drives men to all the ways we see in use of signalizing themselves. Burke. [ 1913 Webster ]

2. To communicate with by means of a signal; as, a ship signalizes its consort. [ 1913 Webster ]

3. To indicate the existence, presence, or fact of, by a signal; as, to signalize the arrival of a steamer. [ 1913 Webster ]

adv. In a signal manner; eminently. [ 1913 Webster ]

n.; pl. -men A man whose business is to manage or display signals; especially, one employed in setting the signals by which railroad trains are run or warned. [ 1913 Webster ]

n. The act of signaling, or of signalizing; hence, description by peculiar, appropriate, or characteristic marks. Mrs. Browning. [ 1913 Webster ]

n. (Electronics, Information science, Experimental science) The ratio of the intensity of a signal{ 2 } to the background noise detected by a measuring instrument, especially in a communications channel; the higher the ratio, the more accurately the information contained can be interpreted. The term is applied not only to human communications, but to the detection of information in any system that is being studied to gain knowledge; as, the signal-to-noise ratio of light signals in older optic fibers drops to an unusable level after several miles.. [ PJC ]

{ or } [ After Lieut. Samuel W. Very, who invented the system in 1877. ] (Naut.) A system of signaling in which balls of red and green fire are fired from a pistol, the arrangement in groups denoting numbers having a code significance. The pistol used to fire the signal flare is called a
Very pistol. [ Webster 1913 Suppl. +PJC ]

. Any signal giving information about the weather. The system used by the United States Weather Bureau includes temperature, cold or hot wave, rain or snow, wind direction, storm, and hurricane signals. [ Webster 1913 Suppl. ]

. In general, any signal announcing information concerning winds, and esp. the expected approach of winds whose direction and force are dangerous to shipping, etc. The wind-signal system of the United States Weather Bureau consists of storm, information, hurricane, hot wind, and inland storm signals. [ Webster 1913 Suppl. ]