Note 40 — Chapter III · EARLY MEDIÆVAL DESIGN
Reading edition
Buttress: A mass of material, usually masonry, intended to resist, by its dead weight, the thrust of an arch, or vault, or, more rarely, the spread of a framed roof or the like.
Flying buttress: A sloping bar of stone, supported on an arched structure which serves to carry the thrust of an arch or vault across a space to the buttress beyond.