The acronym BWR stands for ‘Boiling Water Resistant’. It?s an exterior grade waterproof plywood, that is better than MR grade plywood. It is the preferred choice of material for making those pieces of furniture that are likely to get wet. Example, Kitchen cabinets and other Kitchen furniture. It’s also costlier than MR grade ply. Note: There is also another grade known as BWP, which is more commonly used with block boards. Similar to BWR grade plywood, BWP block boards are also of an exterior grade having waterproofing qualities.