From ek and pipto; to drop away; specially, be driven out of one's course; figuratively, to lose, become inefficient -- be cast, fail, fall (away, off), take none effect.
KJV: And, behold, the angel of the Lord came upon him, and a light shined in the prison: and he smote Peter on the side, and raised him up, saying, Arise up quickly. And his chains fell off from his hands.
NASB: And behold, an angel of the Lord suddenly appeared and a light shone in the cell; and he struck Peter's side and woke him up, saying, "Get up quickly." And his chains fell off his hands.
KJV: Which when they had taken up, they used helps, undergirding the ship; and, fearing lest they should fall into the quicksands, strake sail, and so were driven.
NASB: After they had hoisted it up, they used supporting cables in undergirding the ship; and fearing that they might run aground on the shallows of Syrtis, they let down the sea anchor and in this way let themselves be driven along.