Where does “Arier” come from?

Arier (German) comes from Sanskrit आर्य, from Pali อริย — Thai script form of ariya.

Arier (German): Aryan

Definitions

Step	Language	Word	Meaning
1	Sanskrit	आर्य	an Indo-Aryan, i.e. an Ārya, a self-designator of...
2	Pali	อริย	Thai script form of ariya

Arier — Etymology, Origin & Word History | Etymology Explorer