Easton's Bible Dictionary (1897)
Safe in strength, the chief ruler of the synagogue at Corinth, who was seized and beaten by the mob in the presence of Gallio, the Roman governor, when he refused to proceed against Paul at the instigation of the Jews (Acts 18:12-17). The motives of this assault against Sosthenes are not recorded, nor is it mentioned whether it was made by Greeks or Romans. Some identify him, but without sufficient grounds, with one whom Paul calls “Sosthenes our brother,” a convert to the faith (1 Cor. 1:1).
Smith's Bible Dictionary (1863)
(saviour of his nation) was a Jew at Corinth who was seized and beaten in the presence of Gallio.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
SOS'THENES (safe in strength), a ruler of the Jewish synagogue at Corinth. He was seized and beaten in that city by a party of Greeks, who were thus excited to acts of violence by what they thought the unjustifiable and malicious persecution of Paul. Acts 18:17. It is thought that he afterward became a convert to the Christian faith. 1 Cor 1:1-2.
Hitchcock's Bible Names (1869)
savior; strong; powerful