Where does “ӯстод” come from?

ӯстод (Tajik) comes from Middle Persian ʾwstʾt', from Proto-Iranian Hawastātas, from Proto-Iranian HawastaHyáti, from Proto-Iranian Hawa-.

Ancestry of “ӯстод”, step by step

ӯстод traces back through two separate lines of ancestry.

via Middle Persian ʾwstʾt'

StepLanguageWordMeaning
1Middle Persianʾwstʾt'master, craftsman
2Proto-IranianHawastātas—
3Proto-IranianHawastaHyáti—
4Proto-IranianHawa-—

via Middle Persian ???????

StepLanguageWordMeaning
1Middle Persian???????master, craftsman
Every word from Proto-Iranian Hawa- →Every word from Proto-Iranian HawastaHyáti →Every word from Proto-Iranian Hawastātas →