to utter intentions of injury or punishment against:(verb.communication)
Example: He threatened me when I tried to call the police.
source: wordnet30
to be a menacing indication of something:(verb.communication)
Example: The clouds threaten rain.
Danger threatens.
source: wordnet30
To utter threats against; to menace; to inspire with apprehension; to alarm, or attempt to alarm, as with the promise of something evil or disagreeable; to warn.(verb)
source: webster1913
To use threats, or menaces; also, to have a threatening appearance.(verb)