vagina: Latin = sheath; hence, invagination is the acquisition of a sheath by pushing inwards into a membrane, and evagination is similar but produced by pushing outwards.
vagus: Latin = wandering; hence, cranial nerve X, which leaves the head and neck to traverse the thorax and upper part of the abdomen.
vallate: Latin vallatus = walled; hence, the large papillae on the tongue which are depressed below the surface and are surrounded by a groove which is itself bounded by a wall.