Strong’s Greek
G204 — akrogoniaios
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀκρογωνιαῖος
akrogoniaios — pronounced ak-rog-o-nee-ah'-yos
from 206 and 1137; belonging to the extreme corner:--chief corner. see GREEK for 206 see GREEK for 1137
2 occurrences in the KJV.
Ephesians 2:20
And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone;
1 Peter 2:6
Wherefore also it is contained in the scripture, Behold, I lay in Sion a chief corner stone, elect, precious: and he that believeth on him shall not be confounded.