coonass

1960–65 or earlier; probably alteration, by folk etymology, of Louisiana French, French conasse a contemptuous term for a woman, literally, vulva, equivalent to con vulva (< Latin cunnus) + -asse pejorative noun suffix

This vulgar slang term is used with disparaging intent and is perceived as insulting. It is most likely not connected with the derogatory use of coon to refer to a black person.