Where does “сухость” come from?

сухость (Russian) comes from Russian сухо́й, from Proto-Slavic sȗxъ, from Proto-Balto-Slavic *saušás, from Proto-Indo-European sh₂ewsos.

сухость (Russian): dryness

Definitions

Step	Language	Word	Meaning
1	Russian	сухо́й	dry
2	Proto-Slavic	sȗxъ	dry
3	Proto-Balto-Slavic	*saušás	—
4	Proto-Indo-European	sh₂ewsos	—

сухость — Etymology, Origin & Word History | Etymology Explorer