PROCONSUL . This was originally two words proconsule , meaning a magistrate with the insignia and powers of a consul. When the kingship was abolished in Rome it gave place to a rule of two men, not called by the now detested name, but named prætores (‘generals’) or consules (‘colleagues’). As the Roman territory increased, men of prætorian or consular rank were required to govern the provinces (wh. see). During the Empire all governors of senatorial provinces were called proconsuls, whether they were ex-consuls and governed important provinces like Asia and Africa, or merely ex-prætors, like Gallio ( Acts 18:12 AV [Note: Authorized Version.] deputy ), who governed a less important province, Achaia .
A. Souter.