It's a linguistic phenomenon where when two words happen so often in combination then the one that least frequently stands alone ends up acquiring the meaning of the whole combination.

"ethnic minority problems" -> "ethnic problema"

I think i messed up that one. I wanted to specify which ethnic groups he was hating in his messages that showed up in court documents so certain details are not missed out.

Ethnics are people that aren't similar to you. Drop in for foreign.