What is Wall?
Wall is (noun) 1. a structure made from things such as bricks or stones, built up to make one of the sides of a building, of a room or to surround a space The walls of the restaurant are decorated with pictures of film stars. There’s a clock on the wall behind my desk. He got into the house by climbing over the garden wall. The garden is surrounded by an old stone wall. 2. to drive or send someone up the wall to make someone very annoyed (informal.) The noise of the pneumatic drills outside the office is sending me up the wall.
source: Easier English, Student Dictionary Upper Intermediate Level