Synonyms for ominous

Adjective

1. baleful, forbidding, menacing, minacious, minatory, ominous, sinister, threatening, ugly, alarming (vs. unalarming)

usage: threatening or foreshadowing evil or tragic developments; "a baleful look"; "forbidding thunderclouds"; "his tone became menacing"; "ominous rumblings of discontent"; "sinister storm clouds"; "a sinister smile"; "his threatening behavior"; "ugly black clouds"; "the situation became ugly"

2. ill, inauspicious, ominous, unpropitious (vs. propitious)

usage: presaging ill-fortune; "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"