That is untrue.

The term "free software" was effectively coined by RMS & The Free Software Foundation. It is used explicitly when referring to copyleft licenses, which restrict certain uses of the licensed software in order to protect user freedoms. You can argue that other people use the term in other ways, but the most commonly accepted definition is the one used by the FSF.

The term "open source" is somewhat vague. Software that is merely "open source" is not necessarily licensed in a way that allows redistribution/modification. The only thing guaranteed about "open source" software is that you can read the source.