[{"Bold_text": "noun", "List Items": ["any of various alloys or metallic substances with a dark gray or blackish color or finish, used for chains, belt buckles, etc.", "Also calledgunmetal gray.a dark gray with bluish or purplish tinge.", "a bronze formerly much used for cannon.", "an alloy of 88 percent copper, 10 percent tin, and 2 percent zinc, cast or machined for use in valves, gears, and other parts."]}]