The Collaborative International Dictionary of English v.0.48:
Acclimation \Ac`cli*ma"tion\, n. The process of becoming, or the state of being, acclimated, or habituated to a new climate; acclimatization. [1913 Webster]WordNet (r) 3.0 (2006):
acclimation n 1: adaptation to a new climate (a new temperature or altitude or environment) [syn: acclimatization, acclimatisation, acclimation]