Where does “arðwos” come from?

arðwos (Proto-Italic) comes from Proto-Indo-European h₃erdʰ-, from Proto-Indo-European -wós — Creates adjectives from verb stems.

Ancestry of “arðwos”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	h₃erdʰ-	to increase, grow; upright, high
2	Proto-Indo-European	-wós	Creates adjectives from verb stems

arðwos — Etymology, Origin & Word History | Etymology Explorer