Boss. A small projection or lump of metal on the surface of a medallic or numismatic item. It may be intentional, as part of a design, as with many bosses forming a texture of raised dots (called pebbled surface). Or, it may be unintentional where bosses form from pits or chips in patterns or dies. Cast medals are particularly susceptible to bosses, caused by dirt or captured gasses, these appear on the surface generally near large detail, and this is what is chased off when a medal is said to be cast and chased. The word comes from emboss – a form of repouse, to hammer design from the back – but intentional bosses are either modelled into the design or applied mechanically, as with a dapple tool. See chasing.