What is "cathedral glass"

Cathedral glass is the name given commercially to monochromatic sheet glass, which is thin by comparison with slab glass, may be coloured and is textured on one side.

The name draws from the fact that windows of stained glass were a feature of medieval European cathedrals from the 10th century onwards.

The term cathedral glass is sometimes applied erroneously to the windows of cathedrals as an alternative to the term stained glass. Stained glass is the material and the art form of making coloured windows of elaborate or pictorial design.