The Collaborative International Dictionary of English v.0.48:

Owner \Own"er\, n.
   One who owns; a rightful proprietor; one who has the legal or
   rightful title, whether he is the possessor or not. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

owner
    n 1: (law) someone who owns (is legal possessor of) a business;
         "he is the owner of a chain of restaurants" [syn: owner,
         proprietor]
    2: a person who owns something; "they are searching for the
       owner of the car"; "who is the owner of that friendly smile?"
       [syn: owner, possessor]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "owner":
   beneficiary, cestui, cestui que trust, cestui que use, deedholder,
   feoffee, feudatory, holder, householder, laird, landlady, landlord,
   lord, master, mesne, mesne lord, mistress, possessor, proprietary,
   proprietor, proprietress, proprietrix, rentier, squire,
   titleholder



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

OWNER, property. The owner is he who has dominion of a thing real or
personal, corporeal or incorporeal, which he has a right to enjoy and to do
with as he pleases, even to spoil or destroy it, as far as the law permits,
unless he be prevented by some agreement or covenant which restrains his
right.
     2. The right of the owner is more extended than that of him who has
only the use of the thing. The owner of an estate may, therefore change the
face of it; he may cut the wood, demolish the buildings, build new ones, and
dig wherever he may deem proper, for minerals, stone, plaster, and similar
things. He may commit what would be considered waste if done by another.
     3. The owner continues to have the same right although he perform no
acts of ownership, or be disabled from performing them, and although another
perform such acts, without the knowledge or against the will of the owner.
But the owner may lose his right in a thing, if he permit it to remain in
the possession of a third person, for sufficient time to enable the latter
to acquire a title to it by prescription, or lapse of time. See Civil Code
of Louis. B. 2, t. 2, c. 1; Encyclopedie de M. D'Alembert, Proprietaire.
     4. When there are several joint owners of a thing, as for example, of a
ship, the majority of them have the right to make contracts in respect of
such thing, in the usual course of business or repair, and the like, and the
minority will be bound by such contracts. Holt, 586; 1 Bell's Com. 519, 5th
ed. See 5 Whart. R. 366.