omen   noun [C]
 something that is considered to be a sign of how a future event will take place
 England's victory over France is a good omen for next week's match against Germany.
 There is no famine at present, but the omens for the winter are not good and many people will face starvation.
 The delay at the airport was a bad omen for our holiday.
 Many people believe that a broken mirror is an omen of bad luck.

 ominous   adjective
 Something that is ominous suggests that something unpleasant is likely to happen.
 The by-election result has ominous implications for the government.
 The company's disappointing sales figures are an ominous sign of worse things to come.
 There was an ominous silence when I asked whether my contract was going to be
 renewed.
 The engine had been making an ominous sound all the way from London, so I wasn't surprised when the car broke down.

 ominously   adverb
 I went into the kitchen and found him lying ominously still on the floor.
(Cited from Cambridge International Dictionary of English.)