Katagō (κατάγω, G2609) means to lead down, to bring down, to conduct to a lower place, to bring a ship to shore/land. From kata (down) + agō (to lead/bring). Used in nautical contexts (bringing a ship to harbor) and of bringing persons to a place, especially Paul being brought to safety. Appears in Acts 9:30; 22:30; 23:15,20,28; Romans 10:6.
In Romans 10:6, Paul cites Deuteronomy 30:12–13 in a remarkably creative theological argument: 'Do not say in your heart, "Who will ascend into heaven?" (that is, to bring Christ down [katagagein]) or "Who will descend into the deep?" (that is, to bring Christ up from the dead).' Paul uses katagō to argue that the work of salvation is already accomplished — you need not climb to heaven to bring Christ down (the Incarnation has already happened) or descend to the depths to raise Him (the Resurrection has already happened). The word of faith is near you. This is a profound hermeneutic: Scripture's commands about impossible human feats point to the divine accomplishments that render them unnecessary. Christ has already been brought 'down' and raised 'up.' Our task is not rescue but reception — to believe in our heart and confess with our mouth.