Fausset's Bible Dictionary
Romans 16:23; Erastus, oikonomos , steward or public treasurer of the city, who kept account of the revenues. Latin arcarius . So in inscriptions in Marm. Oxon., 85, Neilos is called oikonomos of Asia. On the other hand Blastus was chamberlain (epi tou koitonos tou basileos ) in a different sense, namely, over the king's bedchamber, a post of honor and intimacy (Acts 12:20).
These files are public domain.
Fausset, Andrew R. Entry for 'Chamberlain'. Fausset's Bible Dictionary. https://www.studylight.org/dictionaries/eng/fbd/c/chamberlain.html. 1949.