a. Suggesting or threatening harm or evil: a sinister smile.
b. Causing or intending harm or evil; wicked: a sinister conspiracy.
a. Portending misfortune or disaster; ominous: sinister storm clouds.
b. Attended by or causing misfortune or disaster: "The day has passed without any sinister accident" (John Quincy Adams).
a. Archaic On the left side; left.
b. 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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus