thankworthy (Middle English) comes from Middle English thanke worth, from Old English þancweorþ, from Old English weorþ, from Proto-Germanic werþaz, from Proto-Indo-European wert-, from Proto-Indo-European wer- — to burn; to cover, heed, notice; squirrel.
Ancestry of “thankworthy”, step by step
thankworthy traces back through 3 separate lines of ancestry.