Who, in scripture, are referred to as bishops or elders.
Bishop – episkopos
1. an overseer
a. a man charged with the duty of seeing that things to be done by others are done rightly, any curator, guardian or superintendent
b. the superintendent, elder, or overseer of a Christian church
(http://www.searchgodsword.org/lex/grk/view.cgi?number=1985)
Elder – meizōn
1. greater, larger, elder, stronger
Priest – hiereus
Never used of church leadership in the New Testament.