'Breastsummer' definitions:

Definition of 'Breastsummer'

From: GCIDE

Breastsummer \Breast"sum`mer\, n. (Arch.) A summer or girder extending across a building flush with, and supporting, the upper part of a front or external wall; a long lintel; a girder; -- used principally above shop windows. [Written also brestsummer and bressummer.] [1913 Webster]