"I'm a friend of Bill's." You're a friend of Bill's what?

Apparently it’s called the double genitive case.

Which is more linguists observing the habit exists and giving it a name, but it’s mildly interesting how old the habit is. Some people call it an Americanism but apparently it has roots in pre-Norman English.

You know, the fact that it’s the “double genitive” was figured out back in posts #6 and#7. So now, it would appear that your posts are not only pointless carping, but repetitively superfluous carping, to boot. :rolleyes:

So we just need the OP to come back and thank us for googling it for him.

There is a third, which “a photograph that Bob took.”

I was showing someone at work a book I was reading, called Chaos: Making a New Science. My boss walked over and said, “Oh, is that Gleick’s book?” I said, “No, it’s mine.” He turned it over to show that the cover said the author was James Gleick.

Moderator Note

What we really need is for you to stop being snippy. This is GQ. Just stick to the facts.

This isn’t helpful, either.

Why do living things have limbs, fins, wings, flagella? Well, to get around, obviously. Questioned answered. Why would anyone be curious about how they evolved?

You seemed to be flailing around trying to argue against a straw man. Sure, language is defined by consensus usage, sometimes idiomatic and apparently illogical, it does not derive from perfectly consistent prescribed rules. But I don’t see anyone in this thread (including the OP) disputing that. You seem to want to take this correct idea to a preposterous extreme, that we must therefore just unthinkingly accept all language at superficial face value, and that even any curiosity about the nature of language is misguided.

I thought the OP was an interesting question - I’m certainly interested in the history of this idiom and in trying to appreciate the cognitive process that underlies it, and I’ve learned something here.

ETA: posted before I saw mod note. But I think it’s okay to leave my comment in, I was trying to make a substantive point, and (I hope) not junior-mod.

And I thought I was a grammar nazi!