Speculation

 
The word speculation means a guess; a message expressing an opinion based on incomplete evidence; a hypothesis that has been formed by speculating or conjecturing (usually with little hard evidence);and an investment that is very risky but could yield great profits.

Speculation was a also a mild but rather noisy domestic gambling game which appeared towards the end of the 18th century and disappeared about a hundred years later. Jane Austen mentioned it several times, notably in 'Mansfield Park'.