“French” is a gentile adjective.
The non-Jewish friend of a rabbi is an example of someone who might be described as the rabbi's gentile friend.
The non-Mormon friend of a person who is a member of a Mormon church is an example of someone who would be described as gentile.
Origin of gentile
- Middle English gentil from Late Latin gentīlis pagan from Latin of the same clan gentle
From American Heritage Dictionary of the English Language, 5th Edition