The Greek noun akron (ἄκρον) refers to the extreme point or tip of something — the end, top, edge, or outermost limit. It can refer to a fingertip, the ends of the earth, or the extremities of the sky.
Jesus describes gathering the elect from the ends of the earth to the ends of heaven (Mark 13:27) — the comprehensive scope of the final gathering. The rich man asks for just the tip (akron) of his finger dipped in water (Luke 16:24) — a poignant image of too-late longing. God's reach is from extremity to extremity; His salvation extends to the uttermost (Hebrews 7:25).