An opening in a door for pets to come in and out of the house without requiring a human to open the door.

A door that slides into the wall.

In an adjacent building, room or place.

(dialectal) Next door to.

(usually postpositive) That is in an adjacent place; that is located next door.

The door, or one of a set of doors, on a garage, allowing to close the entrance.

(automotive, rail transport) A door designed for use on a car (whether a railway carriage or an automobile).

A door normally leading to a storm cellar, cellar or a basement, for protection from a tornado or a violent storm.

A fireproof door designed to stop fires spreading through buildings. / The door of a furnace offering access to the fire inside.

A door that rotates around a central pivot. / (figuratively) A system or institution in which people exit and immediately reenter.