akrogoniaios identifies the cornerstone in the cited building and Zion imagery.

The two cited uses present the term in cornerstone imagery: in 1 Peter 2:6 a chosen and valued stone is laid in Zion, while in Ephesians 2:20 it is named within the statement that Christ Jesus himself stands in relation to the apostles-and-prophets foundation.

1. Cornerstone in Zion and foundation imagery · dominant

   In 1 Peter 2:6, the accusative singular masculine form occurs in the clause about laying a chosen, valued stone in Zion; the APB renders the clause "I am laying in Zion a chosen, valued cornerstone." In Ephesians 2:20, the genitive singular masculine form occurs as Christ Jesus is described in relation to the foundation of apostles and prophets; the APB renders "Christ Jesus himself being the cornerstone."

   1 Peter 2:6Ephesians 2:20

In the Anselm Project Bible: Across both cited verses, the APB uses "cornerstone" in its presentation of the building and Zion imagery. This rendering is treated as confirmation of the clauses rather than a precise mapping of each form.