Today’s word from list 4 of the Academic Word List is
The two forms of this word are ethnic, ethnically and ethnicity
The more common word combinations are:
and, very sadly, ethnic cleansing
It is also found in combination with these similar ideas:
ethnic and religious
cultural and ethnic
You should also note that it has developed a new-ish (and slightly less precise) meaning close to “exotic”. So ethnic music is not necessarily “ethnic” at all – just from a different place and slightly “different”.