uncertainty

A mass noun for the feeling or the climate of doubt. Middle English had it as uncerteynte: either un- added to certainty, or -ty added to uncertain, and both routes give the same word. It can name the manner of a single remark, as when the American novelist Winston Churchill's The Celebrity (1897) has someone answer "at first with uncertainty." It can also name a condition a whole industry lives under. In the plural it becomes a specific open question.

Here doubt is counted. Each uncertainty is one unsettled point, and the plural uncertainties lets them be gathered, listed and weighed. A typical construction is concessive: despite these uncertainties, someone presses ahead anyway. This shows the word naming obstacles to acknowledge rather than a state of mind. Where the mass noun describes how someone feels, this sense describes what remains to be settled.

Science and mathematics turn the word into a quantity. It measures how widely the values that could reasonably be attributed to a measured quantity are spread. It is typically expressed as a standard deviation or as a confidence interval around the reported result. A careful report therefore states its uncertainty rather than merely confessing to it. Unlike everyday doubt, it can be calculated and narrowed.