officialdom vs brass

officialdom and brass both are nouns.

Word	Noun	Adjective	Verb	Adverb
officialdom	Yes	No	No	No
brass	Yes	No	No	No

As nouns, brass is a hypernym of officialdom; that is, brass is a word with a broader meaning than officialdom:

officialdom: people elected or appointed to administer a government
brass: the persons (or committees or departments etc.) who make up a body for the purpose of administering something

Other hypernyms of officialdom include administration, establishment, governance, governing body, organisation, organization.

officialdom (noun)	brass (noun)
people elected or appointed to administer a government	a wind instrument that consists of a brass tube (usually of variable length) that is blown by means of a cup-shaped or funnel-shaped mouthpiece
	a memorial made of brass
	an ornament or utensil made of brass
	impudent aggressiveness
	the persons (or committees or departments etc.) who make up a body for the purpose of administering something
	the section of a band or orchestra that plays brass instruments
	an alloy of copper and zinc