Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
What's the opposite of open source? Hint: The answer is quite straight-forward. And it's not what some analysts and insiders would have you believe.
The definition of "open source" (as applied to software) is almost universally accepted as that of the Open Source Initiative. Per the OSI, "open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with [certain] criteria" that are outlined on the OSI's Web site. Open-source software, per the OSI, is free, "free" as in "free beer" rather than necessarily as in "free speech," which latter usage of "free" carries with it certain responsibilities. Those responsibilities are "vitally important" according to Richard Stallman and other free-software movement proponents.
There's nothing (so far as I can tell) in the free-software movement or in the OSI definition that says that open-source (or free) software can't be commercial. "Commercial," to me, means that involved persons or organizations have profit motives, that they derive financial or other tangible business benefits from their work on open-source (or free) software. "Commercial" is not the opposite of "open source."
And there's nothing (so far as I can tell) in the free-software movement or in the OSI definition that appoints "proprietary" as the opposite of "open source."