a large flat object that you open when you want to enter or leave a building, room, or vehiclea little cottage with a red door
The door creaked slowly open.
There was a draught coming from under the door.
open/close/shut the door: The police officer told him to open the car door.
Shut the door – it’s cold in here!
knock on the door (=so that someone knows you are there): I knocked on the door and a voice answered ‘Come in’.
be at the door (=be outside the door to someone’s house): There’s someone at the door.
answer/get the door (=go to your door to see who is there): Go and answer the door, will you?
bang/slam the door (=close it noisily): He ran out, slamming the door behind him.
door to/into: The door to the kitchen was open.
back/front/side etc door: Be sure to lock the back door when you leave.
bedroom/shed/car etc door: The bathroom door was shut.