vesicle: Meaning and Definition of

ves•i•cle

1. a small sac or cyst.
2. a small bladderlike cavity, esp. one filled with fluid.
3. a circumscribed elevation of the epidermis containing serous fluid; blister.
4. a small, usually spherical cavity in a rock or mineral, formed by expansion of a gas or vapor before the enclosing body solidified.