Brown-Driver-Briggs (BDB)
H657a
H657a אֶ֫פֶס , אָ֑פֶס prop. ceasing , hence . end , extremity . Expressing non-existence H657b אֹ֫פֶס only in the du . lit. the two extremities, i.e. either the soles of the feet, or the ankles
Brown-Driver-Briggs Hebrew Lexicon (BDB), 1906 — public domain