a crystal ball

a crystal ball

COMMON You talk about a crystal ball when you are saying how difficult it is to predict the future. What you really need to help you select your new car is a crystal ball to tell you how much it will be worth in three or four years' time. Note: You can call the activity of predicting the future crystal ball gazing. Can I ask you now to do a bit of crystal ball gazing? How high do you think the price of oil could go? Note: A crystal ball is a glass ball used by some traditional fortune-tellers (= people who predict what will happen to you in the future). They say that they can see visions of future events within the ball.
See also: ball, crystal