The Collaborative International Dictionary of English v.0.48:

Occupant \Oc"cu*pant\, n. [L. occupans, p. pr. of occupare: cf.
   F. occupant. See Occupy.]
   1. One who occupies, or takes possession; one who has the
      actual use or possession, or is in possession, of a thing;
      as, the occupant of the apartment is not at home.
      [1913 Webster]

   Note: This word, in law, sometimes signifies one who takes
         the first possession of a thing that has no owner.
         [1913 Webster]

   2. A prostitute. [Obs.] --Marston.
      [1913 Webster]

WordNet (r) 3.0 (2006):

occupant
    n 1: someone who lives at a particular place for a prolonged
         period or who was born there [syn: resident, occupant,
         occupier] [ant: nonresident]

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "occupant":
   addressee, artist-in-residence, boarder, denizen, dweller,
   habitant, hirer, homesteader, house detective, householder,
   incumbent, inhabitant, inhabiter, inmate, inpatient, intern,
   leaseholder, lessee, live-in maid, liver, locum tenens, lodger,
   occupier, owner, paying guest, renter, residencer, resident,
   resident physician, residentiary, resider, roomer, sojourner,
   squatter, sublessee, subtenant, tenant, tenant at sufferance,
   tenant for life, underlessee



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

OCCUPANT or OCCUPIER. One who has the actual use or possession of a thing.
     2. He derives his title of occupancy either by taking possession of a
thing without an owner, or by purchase, or gift of the thing from the owner,
or it descends to him by due course of law.
     3. When the occupiers of a house are entitled to a privilege in
consequence of such occupation, as to pass along a way, to enjoy a pew, and
the like, a person who occupies a part of such house, however small, is
entitled to some right, and cannot be deprived of it. 2 B. & A. 164; S. C.
Eng. C. L. R. 50; 1 Chit. Pr. 209, 210; 4 Com. Dig. 64; 5 Com. Dig. 199.