Timber

 While we were out walking on Sunday, my wife and I had the following exchange:

W.:,"What does 'Zimmer' mean in German?"
I: "room". 
W.: "What does Zimmermann mean?"
I: "Carpenter. Hmm."

 A look at the Grimms' dictionary shows that "Zimmer" derives from roots cognate with the English "timber", and originally applied to buildings of wood and to wood suitable for building, then to portions of such a building. So a Zimmermann would be just who one needed to build a Zimmer.

And I don't know why it occurred to my wife to ask.