Where does “tridinge” come from?
tridinge (Middle English) comes from Old English þriðing, from Old Norse þriðjungr, from Proto-Germanic þridjô, from Proto-Indo-European tretyós, from Proto-Indo-European tr̥tyós, from Proto-Indo-European tréyes — three.
Ancestry of “tridinge”, step by step
Words derived from “tridinge”