A functionary is a minor official who works for a government or political party; they attend to administrative tasks that are small and trivial.
A perfunctory action is done with little care or interest; consequently, it is only completed because it is expected of someone to do so.
Two items are fungible if one can be exchanged for the other with no loss in inherent value; for example, one $10 bill and two $5 bills are fungible.
Something that is defunct is no longer in existence or does not function.
A function is a purpose that something has or the work or action that it is able to do.
designed for or capable of a particular function or use
capable of serving a purpose well
fail to function or function improperly
Differentiated vocabulary for your students is just a click away.