The Greek word “diakatelenchomai”

Limited to Acts 18:28, the Greek verb “diakatelenchomai” meant “thoroughly refute.”  The KJV translates this “mightily convince” and the NIV reads, “vigorously refuting.”  Apollos “‘powerfully confuted the Jews in public, showing by the Scriptures that the Christ was Jesus’” (Exegetical Dictionary of the New Testament, 1:302).