Menacing; threatening: ominous black clouds; ominous rumblings of discontent. (adjective)
Of or being an omen, especially an evil one.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "ominous" in a sentence
"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."