1. baleful, forbidding, menacing, minacious, minatory, ominous, sinister, threatening

threatening or foreshadowing evil or tragic developments

Example Sentences:
'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'

Synonyms

• baleful
• forbidding
• menacing
• minacious
• minatory
• ominous
• sinister

2. heavy, lowering, sullen, threatening

darkened by clouds

Example Sentences:
'a heavy sky'

Synonyms

• heavy
• lowering
• sullen