This is a name given to a “hand” of cards that contain no cards higher than a nine. It is used in the game of Contact Bridge. The name was given to this hand by Lord Charles Anderson Worsley, the 2nd Earl of Yarborough.
The probability of getting a Yarborough is which which is or about .
The Earl offered £1,000 to anyone who achieved a "Yarborough" – on condition they paid him £1 each time they did not succeed in getting one.