Where does “kaksoisveli” come from?

kaksoisveli (Finnish) comes from Finnish kaksois-, from Finnish kaksi, from Proto-Finnic kakci, from Proto-Uralic *kakta.

kaksoisveli (Finnish): twin brother

Definitions

Step	Language	Word	Meaning
1	Finnish	kaksois-	double, binary, twin
2	Finnish	kaksi	two
3	Proto-Finnic	kakci	two
4	Proto-Uralic	*kakta	—

kaksoisveli — Etymology, Origin & Word History | Etymology Explorer