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 able to gouge freely on service and
upgrade charges after the initial sale has locked the customer in. Often
used in the phrase proprietary crap
.
3. Synonym for closed-source, e.g. software issued in binary without source and under a restrictive license.
Since the coining of the term open source, many hackers have made a conscious effort to distinguish between proprietary and commercial software. It is possible for software to be commercial (that is, intended to make a profit for the producers) without being proprietary. The reverse is also possible, for example in binary-only freeware.