The space, often unfinished and with sloped walls, directly below the roof in the uppermost part of a house or other building, generally used for storage or habitation. (noun)
Examples of word attic
Dacian captives on the attic (_attic_ = a species of subordinate story added above the main cornice) of this arch were a fortunate addition, furnishing a _raison-d’être_ for the columns and broken entablatures on which they rest.
Her face shone brightly, as if the word attic was “ice cream.”
On the other hand, a disconnected furnace vent in the attic is a SERIOUS defect that could cause a ridiculous amount of damage over a period of just one heating season.
Of the various things you mentioned, the attic is a likely source of heat loss.
The twins caught some of our enthusiasm, and they stopped howling and fighting and biting when we mentioned the word attic.