A yellowish alloy of copper and zinc, sometimes including small amounts of other metals, but usually 67 percent copper and 33 percent zinc. Ornaments, objects, or utensils made of this alloy. Music The section of a band or an orchestra composed of brass instruments. Often used in the plural. Music Brass instruments or their players considered as a group. Often used in the plural. A memorial plaque or tablet made of brass, especially one on which an effigy is incised. A bushing or similar lining for a bearing, made from a copper alloy. Informal Bold self-assurance; effrontery. Slang High-ranking military officers or other high officials. Chiefly British Money.