1.State one's intention to take hostile action against (someone) in retribution for something done or not done.
‘how dare you threaten me?'
‘the men threatened staff with a handgun'
‘‘I might sue for damages,' he threatened'
‘We want to send a clear message to management that they cannot single out and threaten union members.'
‘I am a non-violent person and I would not intentionally threaten Mike or anyone else for that matter.'
2.State one's intention to do (something undesirable) in retribution.
‘the trade unions threatened a general strike'
‘she forced a scene and Toby threatened to leave'
‘His girlfriend has allegedly threatened to kill herself if he dumps her.'
‘He warned clubs threatening to boycott the two-day meeting that they would face sanctions.'
‘They threatened more violence unless Jakarta took action against his killers.'
3.Cause (someone or something) to be vulnerable or at risk; endanger.
‘a broken finger threatened his career'
‘one of four London hospitals threatened with closure'
‘I have, since it was first threatened with closure, been a staunch campaigner both locally and in Parliament to save the maternity unit.'
‘If the nation is threatened with a national crisis, traditional political rivalry is suspended and all parties work together in the interest of national unity.'
‘They are not threatened with relegation yet, but if they do not alter their disappointing curve they could be treading that line before long.'
4.Seem likely to produce an unpleasant or unwelcome result.
‘the dispute threatened to spread to other cities'
‘the air was raw and threatened rain'
‘The day had gotten considerably cooler since lunch and the grey clouds overhead now threatened to rain down on them.'
‘High water boosted the salmon catch for the end of September, and although extreme wind and driving rain threatened to keep anglers at bay, some braved the conditions and got their reward.'
‘The day from about 1 p.m. was dark and wet and in fact a half hour before start, torrential rain threatened to mar the occasion.'
5.(of something undesirable) seem likely to occur.
‘unless war threatened, national politics remained the focus of attention'
‘And now, just to make bad worse, another war was threatening.'
‘Now a war is threatening and loads of boys are packing up to get themselves a piece of the ‘glory'.'
‘When war threatened, von Tempsky offered his services to the Government.'
‘Given his proven record in command, Franz Josef selected Benedek to command the Habsburg North Army in early 1866 when war with Prussia threatened.'