proprietary (adj.)

mid-15c., of clerics, "possessing worldly goods in excess of needs," from Medieval Latin proprietarius "owner of property," noun use of Late Latin adjective proprietarius "of a property holder," from Latin proprietas "ownership; a property" (see property). Meaning "held in private ownership, belonging to an owner" is attested from 1580s.

c. 1400, "proprietor, one who possesses or holds the title to a thing," also "worldly person, person tied to worldly goods or personal comforts," from noun uses of Old French proprietaire and Medieval Latin proprietarius "of a property owner" (see proprietary (n.)). From 1630s in reference to the American colonies, "grantee or owner of a colony" (called proprietary colonies in distinction from charter colonies and royal colonies or provinces.