by chance meaning

• Adverb: by chance
  1. By accident
     - haply [archaic], by luck 
  2. Without advance planning
     - accidentally, circumstantially, unexpectedly 
  3. [archaic] Through chance, "To sleep, perchance to dream.."
     - perchance [archaic]

  Encyclopedia: By chance

• 
  [American idiom]
  by accident; without cause; randomly.
  • The contestants were chosen by chance.
  • We met only by chance, and now we are the closest of friends.
  
• 
  [American slang]
  accidentally; randomly; without planning.
    I found this book by chance at a book sale.
    We met by chance in a class in college.

• (there is) no chance.:    [American slang]Th ...
• chance:    Noun: chance  ...
• chance it:    [American slang]v. ...

Examples

1. a good fortune fell by chance on me last night.
2. no one discovers a rarity by chance.
3. the game was fixed for me by chance.
4. i met him by chance at canterbury cathedral.
5. i met her quite by chance.