The Collaborative International Dictionary of English v.0.48:

Finitude \Fin"i*tude\, n. [L. finire. See Finish.]
   Limitation. --Cheyne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

finitude
    n 1: the quality of being finite [syn: finiteness, finitude,
         boundedness] [ant: boundlessness, infiniteness,
         infinitude, limitlessness, unboundedness]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "finitude":
   caducity, changeableness, corruptibility, death, ephemerality,
   ephemeralness, evanescence, fleetingness, fugacity, impermanence,
   impermanency, instability, momentariness, mortality, mutability,
   perishability, transience, transiency, transientness,
   transitoriness, volatility