One of course checks the Second Edition for correct definitions, not the Third. One has to have standards.
A relief to read this is an ongoing thing. While I haven't kept a list of them, I get the sense in online dictionaries that usages and examples of many words I have used have been edited to reflect very recent and modern trends over the last 10 years. I don't know if there has been any project to track drift in changes to definitions, but somewhere along the way, I stopped fully trusting dictionaries as authorities on definitions and usages as they weren't always reliable as a source to reflect the culture I was raised in. While culture changes, I sensed something insincere and contrived about online dictionaries. I wish I could find an example that sources this belief.
Completely omits mention of ancestry which is how the word is actually used and useful.
"Referring to the origin [...] of such groups" might be it, but yeah, "common and distinctive culture, religion, language, or the like" alone doesn't make an ethnicity. I suspect the existence of ethnic groups will be denied too at some point, or labelled as "offensive".
Oh yes, I overlooked that. I would have thought it would be the only meaning, or at least the first one.