Hebrew and Greek Strong's Dictionary with all the definitions plus combined with every place that word is used in the definitions.
Complete index of every word used in both the Hebrew and Greek Strong's Dictionary in English Word order.
Hebrew and Greek Expanded Dictionary
unthankful 0884 - acharistos {ach-ar'-is-tos}; from 0001 (as a negative particle) and a presumed derivative of 5483; thankless, i.e. ungrateful: -- {unthankful}.