With one's back facing that of somebody else.
Stand back to back so that we can see which of you is taller.
Consecutively; one after the other.
We can't watch these films back to back! That's just way too much for one night.
A house with a party wall at the rear.
Sequential or consecutive.
Ruth and Gehrig hit back-to-back home runs.
With one's back facing that of somebody else.
(of a house) Having a party wall at the rear
We lived in a row of back-to-back houses.