A breeze-block is a big, light, grey building block, used a lot in Britain. It is made of cement mixed with cinders — the leftover ash from a coal fire — and it usually has holes through the middle, so it is cheaper and easier to lift than a solid clay brick. Builders use it for inner walls, garages, and plain buildings; they often cover it with plaster later, because it does not look pretty on its own. Though actually the first half has nothing to do with a light wind. In older British English, breeze meant that furnace ash. Americans usually say cinder block or concrete block for much the same thing. It is everyday building talk, not a fancy word.