They did. "OSI" and "Open Source Initiative" are their trademarks. Which is why people should use these words instead. These do only have one clear meaning.

As far as I know, the term "open source" was coined by the same people who were involved in founding OSI (though the OSI founders were a subset of the people who first used the term). I'd be very curious to see examples of widespread use before 1997 or so.

See the Wikipedia entry: https://en.wikipedia.org/wiki/Open_source

> As far as I know, the term "open source" was coined by the same people who were involved in founding OSI

I think this has been shown to be a bit of a myth.

They claim to have coined it in 1998 but there's evidence of it in use in context without even needing to explain the idea by other people as far back as 1993.

https://groups.google.com/forum/#!msg/comp.os.ms-windows.pro...

Also, the fact is the USPTO wouldn't allow them to trademark it because it has a simple existing descriptive term.

It was a descriptive term used for intelligence (i.e. OSINT) well before 1998. Here's a book from 1976 using the term several times:

https://www.google.com/books/edition/Human_intelligence/VE9s...

You are misinformed. The term "open source" has a history that predates the OSI by at least eight years, possibly longer (but I can only provide cites going back eight years). Please see my full reply here: https://news.ycombinator.com/item?id=26507460

For example, read the last line of this:

http://www.catb.org/~esr/open-source.html