Definition of keep (or lose) one's cool in US English:

keep (or lose) one's cool

phrase

informal
  • Maintain (or fail to maintain) a calm and controlled attitude.

    • ‘William somehow managed to keep his cool and retain control of their car.’
    • ‘We'll teach you how to keep your cool and stay calm in tight situations.’
    • ‘There are two kinds: people who freak out, and people who keep their cool.’
    • ‘The next time something is pushing you to the boiling point, stop and think before you lose your cool and blow up.’
    • ‘Despite the fact that he was vastly outnumbered John never lost his cool, stayed calm and came away with a deserved victory.’
    • ‘He has kept remarkably calm, refusing to lose his cool in the face of constant provocation.’
    • ‘She had to stay calm and keep her cool before the match.’
    • ‘He's trying to get control by making me lose my cool.’
    • ‘Jake was cowering under the bridge, shivering, and panting, but trying to keep his cool and not blow his cover.’
    • ‘I finally lost my cool and told a youngster who'd been particularly loud and obnoxious to sit down and be quiet or I'd have him removed by theater staff.’
    become very angry, fly into a rage, explode, blow up, erupt, lose control, go berserk, breathe fire, begin to rant and rave, flare up, boil over
    View synonyms