Where does “Joos” come from?

Joos (Dutch) comes from Medieval Latin Iodocus, from Breton Iodoc, from Breton iudh, from Proto-Celtic yowdos — judge.

Ancestry of “Joos”, step by step

Step	Language	Word	Meaning
1	Medieval Latin	Iodocus	—
2	Breton	Iodoc	—
3	Breton	iudh	lord
4	Proto-Celtic	yowdos	judge

Joos — Etymology, Origin & Word History | Etymology Explorer