From Middle English sinistre (“unlucky"), from Old French sinistra (“left"), from Latinsinestra (“left hand").
Middle English sinistreunfavorablefrom Old French from Latin sinisteron the left, unlucky
American Heritage Dictionary of the English Language, 5th Edition
Sinister Sentence Examples
There was a moment of sinister silence, then a multitudinous stirring of the leaves.
Shadows made his appearance sinister.
I was in the country when I reached under the seat and retrieved a long and sinister knife.
His face had a sinister, troubled expression; but an enigmatical smile played perpetually around his lips.
By the powers of the Quadruple Alliance this event was regarded as of the most sinister omen, and the question was even raised of a fresh armed intervention in France under the terms of the secret treaty of Aix-la-Chapelle.