Where does “austero” come from?

austero (Spanish) comes from Latin austērus, from Ancient Greek αὐστηρός, from Proto-Indo-European h₂sews- — to be dry.

austero (Spanish): austere

Definitions

Step	Language	Word	Meaning
1	Latin	austērus	—
2	Ancient Greek	αὐστηρός	bitter, harsh
3	Proto-Indo-European	h₂sews-	to be dry

austero — Etymology, Origin & Word History | Etymology Explorer