Definition of keep a (or the) lid on in US English:

keep a (or the) lid on

phrase

informal
  • 1Keep (an emotion or process) from going out of control.

    ‘she was no longer able to keep the lid on her simmering anger’
    • ‘Terri tried to keep a lid on her anger, but was rapidly losing the fight.’
    • ‘He should look at the records of repressive rulers who keep the lid on too tightly.’
    • ‘You may tend to exaggerate, but if you keep a lid on that, you'll be known for your confidence, generosity and sense of justice, lucky Jupiter.’
    • ‘So a baggy post or so per fortnight here is looking like something I can keep a lid on, but the thing is, I really don't want to wreck this blog by turning it into something that looks like a money-extracting device.’
    • ‘He understands the need for more micro-economic reform to achieve the first goal, but also understands that the public's limited appetite for radical reform means he has to keep a lid on.’
    • ‘The expletives with which he greeted reporters after his third round at Gleneagles two Saturdays ago was just another example of the volcanic temper that he has long struggled to keep a lid on.’
    • ‘The only thing that kept the lid on everything was not the secret police or army but a system of intricate favours with just enough people lining their pockets and everyone owing the big man.’
    • ‘He fits the profile of the classic moderate New York Democrat, like his predecessor, who frequently fought to keep a lid on taxes in the city.’
    • ‘He keeps a lid on his feelings, and no one suspects the powerful secrets he has hidden.’
    • ‘He was barely able to keep a lid on them, using secret police and brutal repression.’
    1. 1.1 Keep secret.
      ‘she keeps a very tight lid on her private life’
      • ‘Do you think that major news agencies are keeping the lid on these sort of stories?’
      • ‘The romance was simmering for two years, Daniel revealed, and despite his anxiety to tell everyone, he kept the lid on his newfound love.’
      • ‘It's too difficult for any organization - whether a governmental agency or a news organization - to keep a lid on controversial information in the digital age.’
      • ‘How about keeping a lid on information, Secretary?’
      • ‘It is now known that the government kept the lid on this controversial deployment for more than two weeks.’
      • ‘It's not just the reporters who are keeping a lid on all the good things going on.’
      • ‘They get asked a zillion questions at these press conferences, and mostly they keep a lid on what they've been saying.’
      • ‘But who are the people who are keeping the lid on all this?’
      • ‘The White House is doing an even better job of keeping the lid on this nominee than the last.’
      • ‘Yet competing media outlets, anxious to preserve their access, obligingly kept the lid on.’