Achaia: The name originally of a narrow strip of territory in Greece, on the
north-west of the Peloponnesus. Subsequently it was applied by the
Romans to the whole Peloponnesus, now called the Morea, and the south
of Greece. It was then one of the two provinces (Macedonia being the
other) into which they divided the country when it fell under their
dominion. It is in this latter enlarged meaning that the name is
always used in the New Testament
(Acts 18:12, 27; 19:21; Romans 15: 26; 16:5)
etc. It was at the time when Luke wrote the Acts of the Apostles
under the proconsular form of government; hence the appropriate title
given to Gallio as the "deputy," i.e., proconsul, of Achaia
(Acts 18:12)