Definitions are not static. If the majority of people who say "open source" mean "I can view the source, it is out in the open" vs the OSI definition, then the definition of the word is the former.

Just like how the word "hacker" meant one (generally positive) thing, then it meant computer criminal, and now it has come back to be somewhere in the middle.

Of course it is your right to fight for whichever definition you prefer, but the idea that anyone has a monopoly on the definition and can claim a term "doesn't mean that" is a bit silly.