the structure that covers or forms the top of a building, vehicle, tent etc:
They finally found the cat up on the roof.
We can probably strap the cases to the roof of her car.
a flat roof
a pitched roof (=sloping roof)
a wooden-roofed theatre
the top of a passage under the ground:
Suddenly, the whole tunnel roof caved in.
somewhere to live:
I may not have a job, but at least I've got a roof over my head.
a) also hit the roof
to suddenly become very angry:
Put that back before Dad sees you and hits the roof!
if a price, cost etc goes through the roof, it increases to a very high level
the hard upper part of the inside of your mouth
in the same building or home:
If we're going to live under the same roof, we need to get along.
Here you can buy food, clothes, and electrical goods all under one roof.
in your home:
As long as you live under my roof, you'll do as I say.
8 informal especially American English
if the roof falls in or caves in, something bad suddenly happens to you when you do not expect it