This website contains age-restricted materials including nudity and explicit depictions of sexual activity.
By entering, you affirm that you are at least 18 years of age or the age of majority in the jurisdiction you are accessing the website from and you consent to viewing sexually explicit content.
spoiler
In that case I wonder what they mean by
Given that they actively do a thing where they assign one word to several categories, only one of which is in the puzzle, and the others are red herring categories that do not have four entries, they probably should realize that the most obvious category for these three words is “meta-information about the words” and been a lot more clear with their meaning.
They obviously think this is more general than those ones they say they won’t do.
As another example, we’ve definitely seen ones that are “homophones” before (I can’t remember the specific example, but think: “there”, “their”, “they’re”), and I think we’ve even seen one as simple as “rhymes”, where all 4 words rhymed with each other. Is that more specific than the ones they said they wouldn’t do? I dunno. I’ve never liked that type of category personally, because yeah, it definitely seems pretty unspecific to me.