pro·pri·e·tor·ship \prəˈprīəd.ə(r)ˌship\noun 1. a.: the state or fact of being a proprietor : ownership b.: an exclusive legal right for a definite or indefinite time to the profitable use of corporeal or incorporeal property upon agreed terms < proprietorship of a drug product > < proprietorship of a copyright > 2.: a holding in land < numerous small pleasant proprietorships > 3.: proprietor's equity : net assets