1The bony sheath partly surrounding the base of the styloid process of the temporal bone (now rare).
2An outpouching of peritoneum through the inguinal canal, from which the serous membrane (tunica vaginalis) covering the testicle is derived.
3Either of a pair of plates of the sphenoid bone which articulate with the alae (wings) of the vomer.
Early 18th century; earliest use found in Alexander Monro (1697–1767), surgeon and anatomist. After post-classical Latin processus vaginalis.