sinister
1. [ adjective ] threatening or foreshadowing evil or tragic developments
Synonyms: ominous threatening menacing minacious minatory forbidding ugly baleful
Examples:

"a baleful look" "forbidding thunderclouds" "his tone became menacing" "ominous rumblings of discontent" "sinister storm clouds" "a sinister smile" "his threatening behavior"

Related terms: alarming
2. [ adjective ] stemming from evil characteristics or forces; wicked or dishonorable
Synonyms: dark black
Examples:

"black deeds" "a black lie" "his black heart has concocted yet another black deed" "Darth Vader of the dark side" "a dark purpose" "dark undercurrents of ethnic hostility"

Related terms: evil
3. [ adjective ] (heraldry) on or starting from the wearer's left
Examples:

"bar sinister"

Related terms: heraldry sinistral
Similar spelling:   sinistral
  sinistrorse