Kokoshnik is a semicircular or keel-like exterior decorative element in the Old Russian architecture, a type of corbel zakomara. Unlike zakomara that continues the curvature of the vault behind and carries a part of the vault's weight, kokoshnik is pure decoration and does not carry any weight. Kokoshnik shares its name with the traditional Russian headdress worn by women and girls. The word itself derives from the Old Slavic word kokosh, which refers to a hen or a cockerel.