Hastings' Dictionary of the Bible (1898)
NICOLA'ITANS, an ancient sect whose deeds are expressly and strongly reprobated. Rev 2:6, 2 Sam 20:15. Some have supposed that they were the followers of Nicolas, Acts 6:5, one of the first deacons of the church, whom they regard as having degenerated from the true faith. For this view there is no authority. Others regard the term "Nicolaitans" as a symbolical expression. Since "Nicolas" means "victor of the people," and "Balaam" "devourer of the people," the two. in symbolical unity, signify religious seducers of the people.
It is more probable that the Nicolaitans were identical with those who held the doctrine of Balaam, mentioned in Rev 2:14. Cf. 2 Pet 2:15. So, likely, the Nicolaitans associated fornication and the eating of things sacrificed to idols with an outward profession of Christianity.