WordNet
imperforate hymen
n. hymen that is completely closed so that menstrual blood cannot flow out
Wikipedia
Imperforate hymen
An imperforate hymen is a congenital disorder where a hymen without an opening completely obstructs the vagina. It is caused by a failure of the hymen to perforate during fetal development. It is most often diagnosed in adolescent girls when menstrual blood accumulates in the vagina and sometimes also in the uterus. It is treated by surgical incision of the hymen.