A messenger or envoy officially representing a higher authority. In the Old Testament, an ambassador was someone sent to speak for a king or ruler. This person would go on short trips to share messages or make agreements. They acted as the official voice of the leader who sent them. Examples include:
the envoys of Pharaoh (Isaiah 30:4),
the ambassadors of the rulers of Babylon (2 Chronicles 32:31), and
messengers of Neco, king of Egypt (2 Chronicles 35:21).
In the letters of Paul, the apostle called himself an ambassador for Christ because he had an apostolic mission to share the gospel of Christ with the gentiles (2 Corinthians 5:20; Ephesians 6:20).