The quality or state of being able to be discovered, verified, or determined with certainty.
From ascertainable (able to be determined) with the suffix -ity (quality of). The root ascertain came from Old French a- (to) + certain (sure), meaning to make certain.
Ascertainability is crucial in law and science—if something lacks ascertainability, it's essentially useless as evidence because you can't prove it exists or happened.
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