birth canal

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The passageway through which the fetus is expelled during parturition, leading from the uterus through the cervix, vagina, and vulva.

Wiktionary

1. n. The combined vagina and cervix, when the cervix dilates during birth to form a continuous tube with the vagina.

WordNet 3.0

1. n. a passage in the uterus and vagina through which a fetus passes during vaginal birth