[n] a small anatomically normal sac or bladderlike structure (especially one containing fluid)
bleb, blister, bulla, dacryocyst, dictyosome, follicle, Golgi apparatus, Golgi body, Golgi complex, lacrimal sac, liposome, sac, seminal vesicle, tear sac
\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: (a) (Bot.) A small bladderlike body in the substance of vegetable, or upon the surface of a leaf. (b) (Med.) A small, and more or less circular, elevation of the cuticle, containing a clear watery fluid. (c) (Anat.) A cavity or sac, especially one filled with fluid; as, the umbilical vesicle. (d) (Zo["o]l.) A small convex hollow prominence on the surface of a shell or a coral. (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.