door · noun C /dɔːr/
door
A1 a flat object, often fixed at one edge, that is used to close the entrance of something such as a room or building, or the entrance itself
Dictionary examples:
the front door
the back door
a car door
a sliding door
The door to his bedroom was locked.
We could hear someone knocking at/on the door.
Could you open/close/shut the door, please?
She asked me to answer the door.
Learner example:
There is a garden [outside the] back door but [it] isn't big. (Skills for Life (Entry 1); A1; Thai)
behind closed doors
C2 privately and not in public
Dictionary example:
Most of the deals were made behind closed doors.
Learner example:
Decisions which affect the whole world are made behind closed doors and are top secret. (Certificate of Proficiency in English; C2; Russian)