The Collaborative International Dictionary of English v.0.48:

Inhabitation \In*hab`i*ta"tion\, n. [L. inhabitatio a dwelling.]
   [1913 Webster]
   1. The act of inhabiting, or the state of being inhabited;
      indwelling.
      [1913 Webster]

            The inhabitation of the Holy Ghost.   --Bp. Pearson.
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   2. Abode; place of dwelling; residence. [Obs.] --Milton.
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   3. Population; inhabitants. [Obs.] --Sir T. Browne.
      [1913 Webster]

            The beginning of nations and of the world's
            inhabitation.                         --Sir W.
                                                  Raleigh.
      [1913 Webster]

WordNet (r) 3.0 (2006):

inhabitation
    n 1: the act of dwelling in or living permanently in a place
         (said of both animals and men); "he studied the creation
         and inhabitation and demise of the colony" [syn:
         inhabitancy, inhabitation, habitation]