vesicle

Vesicle \Ves"i*cle\, n. [L. vesicula, dim. of vesica a bladder, blister; akin to Skr. vasti bladder: cf. F. v['e]sicule.] A bladderlike vessel; a membranous cavity; a cyst; a cell. Specifically: [1913 Webster] (a) (Bot.) A small bladderlike body in the substance of vegetable, or upon the surface of a leaf. [1913 Webster] (b) (Med.) A small, and more or less circular, elevation of the cuticle, containing a clear watery fluid. [1913 Webster] (c) (Anat.) A cavity or sac, especially one filled with fluid; as, the umbilical vesicle. [1913 Webster] (d) (Zo["o]l.) A small convex hollow prominence on the surface of a shell or a coral. [1913 Webster] (e) (Geol.) 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. [1913 Webster]