Definition of on the hour in US English:

on the hour

phrase

  • At an exact hour, or on each hour, of the day or night.

    ‘news bulletins on the hour’
    • ‘I can tell you that over the past five days we've done a count every hour on the hour, and it's well under 10 minutes.’
    • ‘I rang every hour, on the hour, until three in the morning, for several nights.’
    • ‘A child's handful of balloons escapes, as they must do every hour on the hour, and floats away over the Magic Kingdom.’
    • ‘Same goes if you're doing it every hour on the hour.’
    • ‘It felt like a gradual poem coming across the TV screen in the same way a news story keeps adding one tiny little detail every hour on the hour.’