brass
/ˈbræs/ /Brit ˈbrɑːs/
noun
plural brasses
[noncount] :a yellow metal that is made by combining copper and zinc
musical instruments (such as trumpets, trombones, and tubas) that are made of brass [noncount]
[noncount] :bright metal objects made of brass
[noncount] chiefly US informal :the people in the highest positions in an organization (such as the military or a business)
Brass is used with both plural and singular verbs in this sense.
(as) bold as brass
get down to brass tacks
informal :to start to discuss or consider the most important details or facts about something