what's a chattel?

[The Squatter of Amon Rûdh]

Your wife was also your chattel but don't go round reminding us feminists or we get upset.

That's odd: I was completely unaware of this, so I checked on dictionary.com and in the Shorter Oxford. They make no mention of a wife being considered a chattel, which is more specifically a piece of moveable
private property. What was your source?

No, Gandalf most certainly did not mean it in that sense; it wouldn't fit the context.