The chief of the synagogue at Corinth, who was beaten by the Gentiles when the Jews carried Paul before Gallio the proconsul, Acts 18:17. He appears to have been the leader of the Jews in this attempt to destroy Paul. Whether he was converted, and is identical with the "Sosthenes our brother" in 1 Corinthians 1:1, is unknown.
These dictionary topics are from American Tract Society Bible Dictionary published in 1859. Public Domain, copy freely.
Rand, W. W. "Entry for 'SOSTHENES'". "American Tract Society Bible Dictionary".