Where does “plusaste” come from?

plusaste (Finnish) comes from Finnish plus, from Latin plūs, from Old Latin plous, from Proto-Indo-European ploh₁is-.

plusaste (Finnish): Synonym of lämpöaste

Definitions

Step	Language	Word	Meaning
1	Finnish	plus	plus
2	Latin	plūs	—
3	Old Latin	plous	—
4	Proto-Indo-European	ploh₁is-	—

plusaste — Etymology, Origin & Word History | Etymology Explorer