Strong’s Greek
G421 — anexichniastos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀνεξιχνίαστος
anexichniastos — pronounced an-ex-ikh-nee'-as-tos
from 1 (as a negative particle) and a presumed derivative of a compound of 1537 and a derivative of 2487; not tracked out, i.e. (by implication) untraceable:--past finding out; unsearchable. see GREEK for 1 see GREEK for 1537 see GREEK for 2487
2 occurrences in the KJV.
Romans 11:33
O the depth of the riches both of the wisdom and knowledge of God! how unsearchable are his judgments, and his ways past finding out!
Ephesians 3:8
Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ;