Vagina \vuh-JAHY-nuh\ , noun;
1. Anatomy: The passage leading from the uterus to the vulva in certain female mammals
Vagina dates to the 1680's from Latin vagina, which meant "sheath, scabbard." It derives from Proto-Indo-European *wag-ina- where *wag means "to break, split, bite."
If you have one, or even if you don't, here are a few interesting facts about the vagina that you may want to know.