mid-15c., "possessing worldly goods in excess of a cleric's needs," from M.L. proprietarius "owner of property," noun use of L.L. adj. proprietarius "of a property holder," from L. proprietas "owner" (see property). Meaning "held in private ownership" is first attested 1580s.
1. In marketroid-speak, superior; implies a product imbued with exclusive magic by the unmatched brilliance of the company's own hardware or software designers. 2. In the language of hackers and users, inferior; implies a product not conforming to open-systems standards, and thus one that puts the customer at the mercy of a vendor who can inflate service and upgrade charges after the initial sale has locked the customer in. [Jargon File]