Strong’s Greek
G5066 — tetartaios
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
τεταρταῖος
tetartaios — pronounced tet-ar-tah'-yos
from 5064; pertaining to the fourth day:--four days. see GREEK for 5064
1 occurrence in the KJV.
John 11:39
Jesus said, Take ye away the stone. Martha, the sister of him that was dead, saith unto him, Lord, by this time he stinketh: for he hath been dead four days.