means The state of not knowing how something will turn out, or of being unable to predict, measure, or fully trust what comes next.

from From the Latin 'certus,' meaning settled, fixed, or decided — itself tied to 'cernere,' to sift, separate, or distinguish (the same root that gives us 'discern' and 'crisis'). Add the negative prefix 'in-' and you get 'incertus,' not-settled, which softened through Old French into English 'certain.' Bolt on the native English 'un-' and the noun-making '-ty,' and you arrive at 'uncertainty': literally the condition of things being unsifted, undecided, still up in the air.