Searching for a reasonable translation of "Zweifamilienhaus" I came across the LEO entry above. Please feel to correct me if I'm wrong, but I would expect a Zweifamilienhaus to be a two-storey house lived in by two families, one per floor (horizontal divide, one main entrance to the house). The division in a semi-detached house is vertical, i.e. two houses sharing a dividing wall, each with its own main entrance.
For the record:
- adjective (of a house) joined to another house on one side only by a common wall.
- noun Brit. a semi-detached house.
© Copyright Oxford University Press 1999 - New Oxford Dictionary of English
That is an accurate description of a Doppelhaushälfte, which is already included in LEO, so this entry could be deleted.
Note that the UK spelling of semi-detached is hyphened. Semidetached without a hyphen may be AE usage?
I still haven't come up with a decent translation for Zweifamilienhaus, though, so if anyone has ideas on that, too, I'd be only happy to hear them!
My Collins suggests "two family house", but I don't feel that that describes the Zweifamilienhaus accurately enough, although it would certainly do if there is nothing more accurate.
Two-family apartment building?
The first related discussion quoted above refers to "duplex", which _might_ cover it, but we don't have duplexes in England, or didn't when I lived there many moons ago. I'm more interested in British usage, since that's my language, but I'm obviously interested to hear what others might say...