Strong's G419 — ἀνεξερεύνητος (adjective)
anexereunetos (an-ex-er-yoo'-nay-tos) adj.
1. not searched out
2. (by implication) inscrutable
[from G1 (as a negative particle) and a presumed derivative of G1830]
KJV: unsearchable 
Root(s): G1, G1830 
Hebrew root: ἐξερευνάω
Occurrences: 1