Where does “влажность” come from?
влажность (Russian) comes from Russian вла́жный, from Russian вла́га, from Old Church Slavonic влага, from Proto-Slavic volga, from Proto-Balto-Slavic wálˀgāˀ, from Proto-Indo-European wolg-eh₂, from Proto-Indo-European welg- — wet, damp.
влажность (Russian): humidity
Ancestry of “влажность”, step by step