Where does “erd-” come from?

erd- (Hungarian) comes from Hungarian -d, from Middle Welsh -nt — 3rd person plural verb ending.

Ancestry of “erd-”, step by step

StepLanguageWordMeaning
1Hungarian-dyour; Used in the second-person singular definite...
2Middle Welsh-nt3rd person plural verb ending
Every word from Middle Welsh -nt →Every word from Hungarian -d →
erd- — Etymology, Origin & Word History | Etymology Explorer