a kind of abutment built archwise, or a mass of stone or brick, serving to prop or support the sides of a building or wall on the outside, where it is either very high, or has any considerable load to sustain on the other side, as a bank of earth, or the like. Buttresses are used against the angles of steeples and other buildings of stone, on the outside and along the walls of such buildings as have great and heavy roofs, which would be subject to thrust out the walls, unless very thick, if no buttresses were placed against them. They are also placed for a support and abutment against the feet of some arches that are turned across great halls in old palaces, abbeys, and the like.