The median slit located inferior and posterior to the external urethral orifice in the female; the exit for menstrual flow and birth and the entrance for the penis during sexual intercourse; the size and appearance of the vaginal orifice varies inversely with that of the hymen (G. membrane), a thin fold of mucous membrane that surrounds the vaginal orifice [ http://www.informatics.jax.org/accession/anna http://www.informatics.jax.org/accession/csmith ]