Where does “bitreuthen” come from?

bitreuthen (Middle English) comes from Middle English treuthe, from Old English trēowþ, from Proto-Germanic triwwiþō, from Proto-Indo-European dóru, from Proto-Indo-European drew- — hard, firm, strong, solid; hard, fast; tree.

Ancestry of “bitreuthen”, step by step

StepLanguageWordMeaning
1Middle EnglishtreutheAlternative form of trouthe; truth
2Old Englishtrēowþtruth, good faith, honour
3Proto-Germanictriwwiþōpromise, contract
4Proto-Indo-Europeandórutree
5Proto-Indo-Europeandrew-hard, firm, strong, solid; hard, fast; tree
Every word from Proto-Indo-European drew- →Every word from Proto-Indo-European dóru →Every word from Proto-Germanic triwwiþō →