proprietary āļāļ·āļāļāļ°āđāļĢ proprietary āļāļ·āļāļāļ°āđāļĢ Of, relating to, or suggestive of a proprietor or to proprietors as a group: had proprietary rights; behaved with a proprietary air in his friend's house. Exclusively owned; private: a proprietary hospital. Owned by a private individual or corporation under a trademark or patent: a proprietary drug. A proprietor.A group of proprietors.Ownership; proprietorship.A proprietary medicine.One granted ownership of a proprietary colony.