Dictionary.net

• barj'-b[=o]rd, n. a board extending along the edge of the gable of a house to cover the rafters and keep out the rain. [The barge here may be conn. with Low L. bargus, a gallows.]

1908 - Chambers's Twentieth Century Dictionary of the English Language
By Thomas Davidson

• n. A board placed at the gable of a building to hide the horizontal timbers of the roof.

1871 - The Cabinet Dictionary of the English Language