资料来源 : Webster's Revised Unabridged Dictionary (1913)

Uncertainty \Un*cer"tain*ty\, n.; pl. {Uncertainties}.
   1. The quality or state of being uncertain.

   2. That which is uncertain; something unknown.

            Our shepherd's case is every man's case that quits a
            moral certainty for an uncertainty.   --L'Estrange.