Definition of: sinister

(sin′is·tər) adjective
1. Morally wrong; malevolent; evil; bad; perverse: sinister purposes; a sinister expression on the face.
2. Boding, tending toward, or attended with disaster; unlucky; inauspicious: from a superstition that omens seen on the left boded ill.
3. Situated on the left side or hand: opposed to right or right-hand.
4. Her. Of a shield, left as regards the wearer; hence, right as regards the observer: opposed to dexter. Compare illustration under ESCUTCHEON. [<F sinistre <L sinister left]
—sin′is·ter·ly adverb
—sin′is·ter·ness noun