British informal Talk about tediously and at length: she’s always on about doing one’s duty
More example sentences
- She was the only person on board who could always understand what he was on about.
- He talked a lot about the virtues of tolerance and fair play, but nobody had a clue what he was on about.
- Half of them texted me back wondering what on earth I was on about.
Definition of be on about in:
- The US English dictionary