> [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 avoiding the negative connotations (to suits) of the term “free software”.
http://www.catb.org/~esr/jargon/html/O/open-source.html
I looks like open source means more that just ability to read the code.