Where does “thirsti” come from?

thirsti (Middle English) comes from Old English þurstiġ, from Proto-Germanic þurstugaz.

Ancestry of “thirsti”, step by step

StepLanguageWordMeaning
1Old Englishþurstiġthirsty
2Proto-Germanicþurstugaz
Every word from Proto-Germanic þurstugazEvery word from Old English þurstiġ