- Suggesting or threatening evil: a sinister smile.
- Presaging trouble; ominous: sinister storm clouds.
- Attended by or causing disaster or inauspicious circumstances.
- On the left side; left.
- Heraldry. Situated on or being the side of a shield on the wearer's left and the observer's right.
[Middle English sinistre, unfavorable, from Old French, from Latin sinister, on the left, unlucky.]
sinisterly sin'is·ter·ly adv.sinisterness sin'is·ter·ness n.
SYNONYMS sinister, baleful, malign. These adjectives apply to what is indicative of or threatens great harm, disaster, or evil. Sinister usually implies impending or lurking danger that makes its presence felt by ominous signs or portents: We heard a sinister laugh from behind the door. Baleful intensifies the sense of menace; it suggests a deadly, virulent, or poisonous quality: The guard's baleful glare frightened the children. Malign applies to what manifests an evil disposition, nature, influence, or intent: “The Devil . . . with jealous leer malign/Eyed them askance” (John Milton).




