Where does “Träistrik” come from?

Träistrik (Saterland Frisian) comes from Saterland Frisian träi, from Old Frisian thrē, from Proto-West Germanic þrīʀ, from Proto-Germanic þrīz, from Proto-Indo-European *tréyes.

Ancestry of “Träistrik”, step by step

StepLanguageWordMeaning
1Saterland Frisianträithree
2Old Frisianthrēthree
3Proto-West Germanicþrīʀthree
4Proto-Germanicþrīzthree
5Proto-Indo-European*tréyes—
Every word from Proto-Indo-European *tréyes →Every word from Proto-Germanic þrīz →Every word from Proto-West Germanic þrīʀ →