SIGNAL n.
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.
SINISTER a.
Indicative of lurking evil or harm; boding covert danger; as, a sinister countenance. Bar sinister. (Her.) See under Bar, n. -- Sinister aspect (Astrol.), an appearance of two planets happening according to the succession of the signs, as Saturn in Aries, and Mars in the same degree of Gemini. -- Sinister base, Sinis…
SIRRAH n.
A term of address implying inferiority and used in anger, contempt, reproach, or disrespectful familiarity, addressed to a man or boy, but sometimes to a woman. In sililoquies often preceded by ah. Not used in the plural. "Ah, sirrah mistress." Beau & Fl. Go, sirrah, to my cell. Shak.