An attic is an unfinished room at the very top of a house, just below the roof. It’s often the setting for creepy stories because it’s a room people don’t go in very often.
A finished attic is extra space you can use for a playroom, bedroom, or storage area. In fiction, it’s a great place to stash crazy people. In Charlotte Bronte’s book Jane Eyre, there’s a madwoman in the attic. Some attics don't even have floors that can be walked on, though — they're just empty space at the top of a house. An attic was originally called an attic storey, from the architectural term Attic order.