stumble

/ˈstəm-bəl/

Middle English, probably of Scandinavian origin; akin to Norwegian dialect stumle to stumble

verb

  1. to fall into sin or waywardness

  2. to make an error : blunder

  3. to come to an obstacle to belief

noun

  1. an act or instance of stumbling

idiom

  1. to find or learn about (something) unexpectedly

I stumbled across/on/upon this book by chance.