Dictionaries are meant to explain and define current use in a language, not prescribe it.
Another kind of case has emerged in recent days. Tottenham Hotspur has shown the yellow card to the Oxford English Dictionary for its new definitions of the words “yid” and “yiddo”. While the dictionary records both words as usually offensive terms for Jewish people, it now also describes them as nicknames for Spurs supporters, noting that the fan-directed usage is “originally and frequently derogatory and offensive, though also often as a self-designation”. The club has issued a statement saying that it has “never accommodated” use of the “Y-word”, and considers the definition “misleading”.
Every time people say that a word or meaning “doesn’t belong” in a dictionary, lexicographers sigh a little. Dictionary writers share a vocation to record a particular language as it is used rather than how anyone, whether Peta or Spurs, would like it to be used. This is especially true of the OED, which is designed as a tool for the historical study of the language, recording evidence of changes in English words and meanings over the past thousand years. It’s worth noting that at this point Oxford Dictionaries has included the “Spurs supporter” definition of the Y-words only in the OED, a subscription-based service intended for those engaged in historical and linguistic research. It does not appear in its web-searchable online products, which are designed for everyday use by people learning or using the language.