One of the many dictionary definitions of Open Source
n. [common; also adj. `open-source'] Term coined in March 1998 following the Mozilla release to describe software distributed in source under licenses guaranteeing anybody rights to freely use, modify, and redistribute, the code. The intent was to be able to sell the hackers' ways of doing software to industry and the mainstream by avoid the negative connotations (to suits) of the term "free software". For discussion of the followon tactics and their consequences, see the Open Source Initiative (http://www.opensource.org) site."
However, the following article posted on the Inquirer, shows that Microsoft beg to differ.
Microsoft "Open Sauces" .NET
In a very proprietary way, complains bloke
have a read a learn the error of our ways.
Thank you Microsoft!