Source : Webster's Revised Unabridged Dictionary (1913)

Transitoriness \Tran"si*to*ri*ness\, n.
   The quality or state of being transitory; speedy passage or
   departure.

Source : WordNet®

transitoriness
     n : an impermanence that suggests the inevitability of ending or
         dying [syn: {transience}, {transiency}]