In science, the Uncertainty Principle says that you cannot precisely measure anything past a certain level of precision because the mere act of observing distorts the object of the measurement.

FORBES: Perfect Numbers

But while so much uncertainty surrounds Khan's future out of the ring, what is certain is his potential class in it.

BBC: Waiting game for Khan

Defined as risk or uncertainty, in a financial context it refers to the sale of items whose existence is not certain.

FORBES: Magazine Article