B2 a suggestion that something unpleasant or violent will happen, especially if a particular action or order is not followed: [+ to infinitive] She carried out her threat to throw away any clothes that were left on the floor. The threat of jail failed to deter him from petty crime. Drunken drivers pose a serious threat (= cause a lot of harm) to other road users. He says he'll tell the authorities but it's just an empty threat (= it will not happen).Dangers and threats be under threat of sth › to be in a situation where people are threatening you with something bad or unpleasant: She left the country under threat of arrest if she returned.Unsafe and insecure