“Get a good dictionary, and look up where the English word “priest” comes from.”
You have this backwards.
I have several great Greek dictionaries. There is no church office of “priest” in the NT.
best.
You won't find an English word as an entry in a Greek dictionary (but I would have thought you knew that!). Consult an English etymological dictionary -- maybe the Oxford English Dictionary or the Century (if you can find an edition no later than 1914.