Ethnicity is the term for the culture of peoples in a geographic region.
Ethnicity is being connected by language, heritage, religion, and customs. To be a member of an ethnic group is to conform to some or all of those practices. etc.
Race is genetics and ethnicity is culture.
Race and ethnicity can overlap, but they are distinct.
A Japanese-American would be a member of the Japanese or East Asian race, but, if they don't practice any of the customs of their ancestors, or have no knowledge of the Japanese language they might not identify with the ethnicity, and instead consider themselves to be American.
When a person has many friends of a certain ethnicity... But they themselves are white. After a certain amount of friends and exposure to culture of a certain racial group, they can be made into an "honoraryethnicity".
"Cara, I've never seen that white girl Alex with anyone who isn't mexican..."
"I think they did the honoraryethnicity ceremony a few weeks ago... She's an honorary mexican now.
In modern use this word should be used in place of Racism as we are all one race but have different ethnographies. A word that should be used to describe prejudice of another ethnicity .