The OSI have their own definition, but to me.. open source is a technological step towards a post-scarcity society. Do rad shit. Release it for free to people who can benefit. Improve it together.
That said, there are realities of open source (like the funding model) which is still very much tied to scarcity. One step at a time.
Commercial Open Source
This is kinda like open source, but with a wrapper that someone tries to sell. Good examples of this are https://flagsmith.com/ and https://gitlab.com/.