A girl who has never had a penis in her mouth.
Even though Suzy had been having sex with her boyfriend Ben for almost a year, she is still a mouth virgin because she is afraid he'll ejaculate in her mouth and she thinks that is disgusting.
Suzy's younger sister Donna, however, is no longer a mouth virgin. She gave Ben a blow job one night when Suzy wasn't home and Ben convinced her that it was ok for her to do it. Ben then took Donna's finger virginity before Suzy returned from the library.
A person that has never engaged in oral sex.
Some of the girls here may still be regular virgins, but none are mouth virgins.