WordWeb Online

1. Indicating evil intent or suggesting tragic developments
   "his threatening behaviour";
   - baleful, forbidding, menacing, minacious, minatory, ominous, sinister
    
2. Darkened by clouds
   "a threatening sky";
   - heavy, lowering[2], sullen, lowery, loury, louring

1. Pose a threat to; present a danger to
   "The pollution is threatening the crops";
   - endanger, jeopardize, jeopardise [Brit], menace, imperil, peril
    
2. To utter intentions of injury or punishment against
   "He threatened me when I tried to call the police"
    
3. To be a menacing indication of something
   "The clouds threaten rain"; "Danger threatens"

See also: alarming, cloudy

Type of: augur, auspicate, be, betoken [archaic], bode, exist, forecast, foreshadow, foretell, foretoken, omen, portend, predict, prefigure, presage, prognosticate, warn

Encyclopedia: Threatening