1. noun /bɹɑːs,bɹæs/
The brass are not going to like this.
b) A class of wind instruments, usually made of metal (such as brass), that use vibrations of the players lips to produce sound.
2. adjective /bɹɑːs,bɹæs/
a) Made of brass.<! Actually attributive noun?
[...] ornamented by one common very brass spur, originally valued at some thirteen cents, [...]
b) Of the colour of brass.
He felt, naturally enough, that his very life depended on his seeming to be for the time a very brass pot, and nothing else.
Wikipedia foundation.