Sig'nal1, n.
n. [Fr. signal, Sp. señal, Pg. sinal, It. segnale, L. Lat. signale, from Lat. signum. See SIGN.]
Sense 1. A sign which has been agreed upon to give notice of some occurrence, command, or danger, to a person at a distance; also, a sign, event, or watchword, which has been agreed upon, as the occasion of concerted action.
All obeyed The wonted signal. Milton.
Sense 2. Hence, a token; an indication; a foreshadowing. “The weary sun . . . gives signal of a goodly day to-morrow.” Shak.
Signal-post, or signal-staff, a pole or mast upon which a flag or any thing else may be displayed for the purpose of conveying signals.