The Collaborative International Dictionary of English v.0.48:

Commorancy \Com"mo*ran*cy\, n.
   1. (Law) A dwelling or ordinary residence in a place;
      habitation.
      [1913 Webster]

            Commorancy consists in usually lying there.
                                                  --Blackstone.
      [1913 Webster]

   2. (Am. Law) Residence temporarily, or for a short time.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

COMMORANCY, persons. An abiding dwelling, or continuing as an inhabitant in
any place. It consists, properly, in sleeping usually in one place.,