Strong’s Greek
G884 — acharistos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἀχάριστος
acharistos — pronounced ach-ar'-is-tos
from 1 (as a negative particle) and a presumed derivative of 5483; thankless, i.e. ungrateful:--unthankful. see GREEK for 1 see GREEK for 5483
2 occurrences in the KJV.
Luke 6:35
But love ye your enemies, and do good, and lend, hoping for nothing again; and your reward shall be great, and ye shall be the children of the Highest: for he is kind unto the unthankful and to the evil.
2 Timothy 3:2
For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy,