minacious
1. [ adjective ] threatening or foreshadowing evil or tragic developments
Synonyms: ominous sinister threatening menacing 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