Uncertainty

n. state of being uncertain, doubtfulness, ambiguity

Uncertainty is a term used in subtly different ways in a number of fields, including philosophy, statistics, economics, finance, insurance, psychology, engineering and science. It applies to predictions of future events, to physical measurements already made, or to the unknown unknown.
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Noun
1. being unsettled or in doubt; "the uncertainty of the outcome"
(synonym) uncertainness
(antonym) certainty, sure thing, foregone conclusion
(hypernym) quality
(hyponym) doubt, dubiousness, doubtfulness, question
2. the state of being unsure of something
(synonym) doubt, incertitude, dubiety, doubtfulness, dubiousness
(antonym) certainty
(hypernym) cognitive state, state of mind
(hyponym) mental reservation, reservation, arriere pensee

(n.)
The quality or state of being uncertain.
  

(n.)
That which is uncertain; something unknown.
  

unmeasurable risk: The decision-making condition where the decision-maker, or manager, cannot assign credible probabilities to alternative outcomes.