Proconsul - Vine's Expository Dictionary of New Testament Words
Proconsul
[ 1,,G446, anthupatos ]from anti, instead of," and hupatos, "supreme," denotes "a consul, one acting in place of a consul, a proconsul, the governor of a senatorial province" (i.e., one which had no standing army). The "proconsuls" were of two classes,
(a) exconsuls, the rulers of the provinces of Asia and Africa, who were therefore "proconsuls"
(b) those who were ex-pretors or "proconsuls" of other senatorial provinces (a pretor being virtually the same as a consul). To the former belonged the "proconsuls" at Ephesus, Acts 19:38 (AV, "deputies"); to the latter, Sergius Paulus in Cyprus, Acts 13:7-Acts 13:8, Acts 13:12, and Gallio at Corinth, Acts 18:12. In the NT times Egypt was governed by a prefect. Provinces in which a standing army was kept were governed by an imperial legate (e.g., Quirinius in Syria, Luke 2:2): See GOVERNOR, A, No. 1.
Note: Anthupateo, "to be proconsul," is in some texts in Acts 18:12.