To cease, fail, have and end: אַפְסֵי – ephes

He shall have dominion also from sea to sea, and from the river unto the ends of the earth.

(Psalms 72:8) KJV

Does this sound like a circumferential precipice at the edge of a flat earth? Or could it be the coast, as in, the beach?

To cease, fail, have and end: אַפְסֵי – ephes

• to cease, fail, have an end.
  1. end, extremity.
  2. dual two extremities, i.e. the soles or ankles of the feet, Eze. 47:3.
  3. adv.
     • (a) no more; none besides, and so with paragogic Yod
     • (b) not, non; without;
     • (c) nothing; of nothing; for nothing;
     • (d) nothing but, only; prop. only that, except, unless.

Davidson Analytical Hebrew and Chaldee Lexicon page XLI

If my feet are at the end of my legs, then the coast is at the end of the land. The ends of the earth is simply where the land stops: it ceases, fails, has and end. The beach.