Source : Webster's Revised Unabridged Dictionary (1913)

Acclimatization \Ac*cli"ma*ti*za"tion\, n.
   The act of acclimatizing; the process of inuring to a new
   climate, or the state of being so inured. --Darwin.

Source : WordNet®

acclimatization
     n : adaptation to a new climate (a new temperature or altitude
         or environment) [syn: {acclimatisation}, {acclimation}]