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

"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 ] presaging ill-fortune
Synonyms: inauspicious ill

"ill omens" "ill predictions" "my words with inauspicious thunderings shook heaven"- P.B.Shelley "a dead and ominous silence prevailed" "a by-election at a time highly unpropitious for the Government"

Related terms: unpropitious
Similar spelling:   ominously