SIGNAL n. 6 definitions
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.
SIGNATURE n. 9 definitions
A sign, stamp, or mark impressed, as by a seal. The brain, being well furnished with various traces, signatures, and images. I. Watts. The natural and indelible signature of God, which human souls . . . are supposed to be stamped with. Bentley.
SIGNBOARD n.
A board, placed on or before a shop, office, etc., on which ssome notice is given, as the name of a firm, of a business, or the like.