stumble across

stumble across (third-person singular simple present stumbles across, present participle stumbling across, simple past and past participle stumbled across)

1. (transitive) To discover or find (something) by accident.
   • 2021 December 1, Nigel Harris, “St Pancras and King's Cross: 1947”, in RAIL, number 945, page 36:

     This magnificent picture really stopped me in my tracks when I stumbled across it. I was drawn inexorably and immediately into the compelling detail discernible on this top-quality image.

2. (transitive) To meet (somebody) by chance.

• come across
• come upon
• stumble on
• stumble upon