Portion of certain blocks projecting outwards from a stone or wooden building, to be worked later to varying degrees, with bossage types including rusticated or economical, and tabular. It is also known as bossed-face masonry.

Its purpose is the subject of debate. According to ancient authors, bossage protected the blocks by cushioning the impact of projectiles from siege engines, although bossage was sometimes used to decorate building exteriors. Bossage may also save time when dressing the stone, speeding up the building’s construction.