om ‧ i ‧ nous /ˈɒmənəs, ˈɒmɪnəs $ ˈɑː-/ BrE AmE adjective
[ Date: 1500-1600 ; Language: Latin ; Origin: ominosus , from omen ]
making you feel that something bad is going to happen:
‘How long will she be ill?’ he asked. There was an ominous silence.
The car is making an ominous rattling sound.
—ominously adverb :
The sky looked ominously dark.