Gnostos (γνωστός) means known, notable, or familiar — either publicly known or personally acquainted. It appears about 15 times in the New Testament. It is used both of personal acquaintances of the disciples (the 'other disciple' who was known to the high priest, John 18:15) and of God's acts being made known publicly (Acts 2:14; 4:10).
Acts uses gnostos repeatedly to frame the proclamation of the early church: 'Let it be known [gnostos] to all of you and to all the people of Israel' (Acts 4:10). Peter's Pentecost sermon launches with the same structure: 'let this be known [gnostos] to you.' The early church was announcing that what was previously hidden — the resurrection, the identity of Jesus — had become gnostos, publicly known and testable. The gospel is not a private experience but a public truth claim. What God has made known in Christ cannot be kept secret — it must be declared (Luke 12:2–3).