What's the singular form of multiethnicity? Here's the word you're looking for.
Answer
The noun multiethnicity is uncountable.
The singular form of multiethnicity is also multiethnicity.
Examples
Multiethnicity is demonstrated by the many churches, synagogues, Hindu temples, and mosques.
Some might argue that Yugoslavia, as a mosaic of southern Slavs and other assorted Balkan peoples, ranked higher on the multiethnicity scale than Slovenia.
