Strong’s Greek
G2121 — eukairos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
εὔκαιρος
eukairos — pronounced yoo'-kahee-ros
from 2095 and 2540; well-timed, i.e. opportune:--convenient, in time of need. see GREEK for 2095 see GREEK for 2540
2 occurrences in the KJV.
Mark 6:21
And when a convenient day was come, that Herod on his birthday made a supper to his lords, high captains, and chief estates of Galilee;
Hebrews 4:16
Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.