From kata ('according to') and holos ('whole'). Katholou means in total, entirely, altogether β used in negative constructions ('not at all') for absolute prohibition. From this root derives the English word 'catholic' (universal).
Acts 4:18 records the Sanhedrin commanding Peter and John 'not to speak at all (katholou) nor teach in the name of Jesus.' The absolute force of this prohibition only highlighted the impossibility of compliance for those who had encountered the risen Christ. Peter's response became one of history's most celebrated assertions of divine authority over human authority: 'Whether it be right in the sight of God to hearken unto you more than unto God, judge ye.' The word's broader root (holos, whole) points to the comprehensive nature of the gospel's claim β Christ is Lord of all, and the gospel is for all nations, hence 'catholic' (universal).