The vagina (from Latin vag?na, literally "sheath" or "scabbard") is a fibromuscular (:wiktionary:fibromuscular) tubular (cylinder (geometry)) tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the oviduct. The Latinate plural (rarely used in English (English language)) is vaginae.

The word vagina is quite often incorrectly used to refer to the vulva or female genitals generally; strictly speaking, the vagina is a specific internal structure.