The word "cuprous" refers to an element or compound containing copper. When looking for synonyms for "most cuprous," words like "coppery," "copper-colored," and "reddish-brown" come to mind. These adjectives are often used to describe the appearance of copper in various contexts, including metals, minerals, and even hair color. Other possible synonyms for "most cuprous" might include "coppery-toned," "copper-tinted," or "copper-like." Regardless of the particular synonym chosen, they all convey the sense of something that is dominated by or suggestive of copper, whether in color, texture, or chemical composition.