little addition: free software is ALWAYS open source, but open source is NOT ALWAYS free software. what you meant is freeware which shouldn't be confused with free software. yeah, the term "free software" sucks, because of it's various possible interpretations. god, or rms as others call him
, suggested the use of free/libre/open source software, FLOSS, but that doesn't sound any better.
I think you meant "open source is ALWAYS free software, but free software is NOT ALWAYS open source". I could write a piece of software and give it away for free but not give you the source code.
I think you missed the point. "Free software" does not mean zero cost; it means that you have the freedom to do what you like with the software. It is therefore necessary to have the source code for the software. PavelJ had the right definition, but your argument emphasizes the point that our language's ambiguity makes it hard to discuss what Free is.