For usage of the term in Christian religion and music, see introit
An introitus is an entrance that goes into a canal or hollow organ. The vaginal orifice is an introitus.
The vaginal introitus has also been used for classifying uterine prolapse:
- 1st degree prolapse: cervix is in the vagina
- 2nd degree: cervix at the level of the introitus
- 3rd degree: cervix comes out of the introitus
- procidentia: the uterus also comes out of the introitus
"Introitus" at Dorland's Medical Dictionary