Data ownership is the act of having legal rights and complete control over a single piece or set of data elements. It defines and provides information about the rightful owner of data assets and the acquisition, use and distribution policy implemented by the data owner.
Techopedia explains Data Ownership
Data ownership is primarily a data governance process that details an organization's legal ownership of enterprise-wide data. A specific organization or the data owner has the ability to create, edit, modify, share and restrict access to the data. Data ownership also defines the data owner’s ability to assign, share or surrender all of these privileges to a third party. This concept is generally implemented in medium to large enterprises with huge repositories of centralized or distributed data elements. The data owner claims the possession and copyrights to such data to ensure their control and ability to take legal action if their ownership is illegitimately breached by an internal or external entity.