- (cytology) A membrane-bound structure within a cell in which materials such as enzymes are transported or stored.
- (anatomy) A sac or cyst, especially one containing fluid.
- (medicine) A blister of the skin.
- (geology) A cavity formed in volcanic rock by entrapment of a gas bubble during solidification.
- (anat., med.) A small cavity or sac filled with fluid; esp., a small, round elevation of the skin containing a serous fluid; blister.
- (bot.) A small, bladderlike sac filled with air or liquid.