a girder extending across a large opening in a building to support the wall above, used primarily over shop-fronts
breastsummer in American English
(ˈbresˌsʌmər, ˈbrest-, ˈbresəmər)
noun
Architecture
a horizontal beam supporting an exterior wall over an opening, as a shop window
Also called: breast beam
Word origin
[1605–15; breast + summer2]This word is first recorded in the period 1605–15. Other words that entered Englishat around the same time include: crater, ideal, inverse, package, series