2.nounA sole owner of an unincorporated business, also called a sole proprietor.
3.nounOne of the owners of an unincorporated business, a partner.
4.noun(history) One or more persons to whom a colonial territory is assigned, like a fief, including its administration.
"From 10 September 1621 till 12 June 1632, Sir William Alexander, styled Earl of Stirling and Viscount of Canada, was proprietor of the Scottish colony Nova Scotia."