1. Having no owner
   - ownerless

Antonym: owned

• professional organization
• professional person
• professional relation
• professional tennis
• professional tennis player
• professional wrestling
• professionalisation
• professionalise
• professionalism
• professionalization
• professionalize
• professionally
• professor
• professorial
• professorially
• professoriate
• professorship
• proffer
• proficiency
• proficient
• proficiently
• profile
• profiler
• profiling
• profit