Brewer's: Attics, Attic Storey
Attics are the rooms in the attic storey, and the attic storey generally is an extra storey made in the roof. In the Roman and Renaissance styles of architecture the low storey above the cornice or entablature is called the “Attic.” Professor Goldstücker derives the word from the Sanskrit attaka (a room on the top of a house). ( See The Transactions of the Philological Society, 1854.)
“Here a gentleman present, who had in his attic More pepper than brains, shrieked: ‘The man's a fanatic.’” Lowell: Fable for Critics (stanza 50).