In the sense that there is a standards organization that published a standard definition. There isn't any legal basis for it, but we should support them.
I think official means endorsed by some authority. There’s no authority here at all - just some private people making up a definition and attaching it to an existing term.
authority does not necessarily mean with the threat of violence. It could mean influence. The OSI are an authority as demonstrated by every major tech company using their definition of opensource.
