ἱερατεύω (cl. = ἱεράομαι) [in LXX chiefly for כָּהַן pi. ;] to be a priest, officiate as a priest: Luk.1:8 (the word is freq. in Inscr.; see LS, see word; Deiss., BS, 215; LAE, 70; Cremer, 734).† (AS)
Thayer:
1) to be a priest, discharge the office of a priest, to be busied in sacred duties
ἱερατεύω
hierateuō
hee-er-at-yoo'-o
Prolongation from G2409; to beapriest, that is, performhisfunctions
ἱερεύς
hiereus
hee-er-yooce'
From G2413; a priest (literally or figuratively)
KJV Usage: (high) priest.
G749 ἀρχιερεύςἀρχιερεύς
archiereus
ar-khee-er-yuce'
From G746 and G2409; the highpriest (literally of the Jews, typically Christ); by extension a chiefpriest
KJV Usage: chief (high) priest, chief of the priests.