a bladderlike vessel; a membranous cavity; a cyst; a cell.-a small bladderlike body in the substance of vegetable, or upon the surface of a leaf.-a small, and more or less circular, elevation of the cuticle, containing a clear watery fluid.-a cavity or sac, especially one filled with fluid; as, the umbilical vesicle.-a small convex hollow prominence on the surface of a shell or a coral.-a small cavity, nearly spherical in form, and usually of the size of a pea or smaller, such as are common in some volcanic rocks. they are produced by the liberation of watery vapor in the molten mass.