I disagree. The open source definition includes quite a bit about the license. There’s an organization (OSI) that works on this, and has for decades. The definition is available at https://opensource.org/osd-annotated

The ability to redistribute and change is as important, I think, as the ability to see the source.

I think you're going to run into the same thing I ran into here https://news.ycombinator.com/item?id=20864837 which is that the term Open Source has been taken over by opensource.org.

Although I suppose you won't get as many downvotes as I did (the reason for which still eludes me)

Open Source has a precise and well widely understood meaning that is entirely related to the license. If you use it to mean something else people will be confused.

You want the word shared source maybe? Or viewable source?

That is not true. "Open source" specifically implies certain rights beyond simply allowing people to view the source code (which is known as "shared source").

Many companies like Microsoft allow people to view the source code to their closed-source products under restrictive licenses, but nobody would claim that these products are "open source" as a result.

"Open" doesn't just mean "viewable."