A.T. Robertson Commentary Luke 19:2

"And behold, a man called by name Zacchaeus; and he was a chief publican, and he was rich." — Luke 19:2 (ASV)

Chief publican (αρχιτελωνης). The word occurs nowhere else apparently but the meaning is clear from the other words with αρχι- like αρχιερευς (chief priest) αρχιποιμην (chief shepherd). Jericho was an important trading point for balsam and other things and so Zacchaeus was the head of the tax collections in this region, a sort of commissioner of taxes who probably had other publicans serving under him.