Strong’s Greek
G82 — adelos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἄδηλος
adelos — pronounced ad'-ay-los
from 1 (as a negative particle) and 1212; hidden, figuratively, indistinct:--appear not, uncertain. see GREEK for 1 see GREEK for 1212
2 occurrences in the KJV.
Luke 11:44
Woe unto you, scribes and Pharisees, hypocrites! for ye are as graves which appear not, and the men that walk over them are not aware of them.
1 Corinthians 14:8
For if the trumpet give an uncertain sound, who shall prepare himself to the battle?