Definition: Anteroom, also known as an entranceway, is a small room or space in a home that leads to another area within the house. Definition: The term "ante-room" refers to any area where the door or doorway leading from one room to another (often termed as an 'entrance') can be found. It's often used for storage purposes or for access to areas not immediately adjacent to the main living area. In other words, an anteroom is a small space that allows entry into another area of a house through its door or doorway.