Sorry but this is not the definition of "open source", I would argue there is only a conceptual and cultural definition of "open source". What you are linking to is The Open Source Initiative (OSI) Foundation's declaration called the "Open Source Definition".

They are a single organization, that have done a tremendous job at trying to come up with a global and shared legal framework to which people can license code under. They have gone so far to come up with a pretty good definition of "open source", but not the definition.

This would be equivalent to saying that "Freedom" is defined by the US Constitution or the Canadian Charter of Rights & Freedoms. It is not, those are both examples of a legal definition of freedom, but neither are the sole authority for the global and cultural concept of "Freedom"