far off: at a distance from someone or something, whether the gap is measured in steps or in standing
This is the ordinary Greek word for being a long way off. It never fixes a distance of its own; it simply places one thing at a remove from another and lets the setting supply the scale. In John 21:8 the boat is not far from the shore, and the writer immediately says how far: about a hundred yards. In Luke 15:20 the son is still a long way off when his father spots him, and the distance is the whole point, because the father runs it.
The same word measures gaps nobody walks. A scribe who answers Jesus well is told he is not far from the kingdom of God (Mark 12:34), and Paul tells the Athenians that God is not far from any one of us (Acts 17:27). Nothing has moved in either case. What is being measured is standing, not steps.
Out of that grows a settled way of speaking. Isaiah promises peace to the far and to the near, and in Jewish usage after him "those far off" became a name for people outside the life Israel shared with God. Peter speaks that way at Pentecost (Acts 2:39), and Ephesians builds an argument on it: people who were once far off have been brought near, and the peace announced went to both the far and the near (ἐγγύς). Read as geography, those lines say almost nothing; read as standing, they say everything the letter is about.