Meaning

• Inauspicious, ominous, unlucky, illegitimate (as in bar sinister).

• Evil or seemingly evil; indicating lurking danger or harm.

  "sinister influences"

• Of the left side.

• On the left side of a shield from the wearer's standpoint, and the right side to the viewer.

• Wrong, as springing from indirection or obliquity; perverse; dishonest.