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