pose a threat to; present a danger to
"The pollution is endangering the crops"
to utter intentions of injury or punishment against
"He threatened me when I tried to call the police"
To make a threat against someone; to use threats.
"The rival gang threatened the local shopkeepers until they stopped selling their products."
In plain English: To threaten means to say you will hurt someone if they do not obey your demands.
"The dark clouds threatened to pour rain on our picnic."
Usage: Use threaten when describing an act of intimidation or warning that harm will occur, such as storm clouds threatening rain. Do not confuse this with the noun form in phrases like "pose a threat," where the word functions differently grammatically.
The word threaten comes from the Old English þrēatnian, which originally meant "to urge, force, or compel." It evolved through Middle English thretenen before becoming the modern form we use today.