Wordnet 3.0
ADJECTIVE (1)
1. 
 having no owner; 
[syn: unowned, ownerless]
The Collaborative International Dictionary of English v.0.48:
Ownerless \Own"er*less\, a.
   Without an owner.
   [1913 Webster]
WordNet (r) 3.0 (2006):
ownerless
    adj 1: having no owner [syn: unowned, ownerless] [ant:
           owned]