Where does “Kosovo” come from?

Kosovo (Vietnamese) comes from English Kosovo, from Serbo-Croatian Косово поље, from Serbo-Croatian косовa, from Serbo-Croatian кос, from Proto-Slavic kosъ, from Proto-Slavic kopsъ.

Ancestry of “Kosovo”, step by step

Step	Language	Word	Meaning
1	English	Kosovo	Considered by the Republic of Serbia to be one of its two autonomous provinces
2	Serbo-Croatian	Косово поље	blackbirds’ field
3	Serbo-Croatian	косовa	—
4	Serbo-Croatian	кос	slant, inclined, skew; blackbird
5	Proto-Slavic	kosъ	blackbird; skew, slanted
6	Proto-Slavic	kopsъ	—

Every word from Proto-Slavic kopsъ →Every word from Proto-Slavic kosъ →Every word from Serbo-Croatian кос →