Of or pertaining to an omen or to omens; being or exhibiting an omen; significant. (adjective)
Specifically, giving indication of a coming ill; being an evil omen; threatening; portentous; inauspicious. (adjective)
Examples of word ominous
Devil's Reef, the Devil's Horse-shoe or by some other term ominous of shipwrecks.
What's even more ominous is that the trendlines aren't all that great, heading into October.
A wave of hateful messages and death threats hit the University, and was joined soon enough by a few political leaders and wealthy donors instructing officials in ominous tones to cancel my visit to the campus.
Within a week, Syria agrees to a returning US Envoy, that should tell you something real ominous is brewing.
He put the question seemingly to the glowing log, and, as if in ominous foreshadow, it flared brightly and crumbled away in a burst of sparks.