"ominous" in the adjective sense
1. baleful, forbidding, menacing, minacious, minatory, ominous, sinister, threatening
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
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"
Source: WordNet® (An amazing lexical database of English)
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