Cyst
Part of speech: noun
Definition: A pouch or sac without opening, usually membranous and containing morbid matter, which develops in one of the natural cavities or in the substance of an organ.
Vesicle
Part of speech: noun
Definition: A membrane-bound compartment found in a cell.A small bladder-like cell or cavity.A small sac or cyst or vacuole, especially one containing fluid. A blister formed in or beneath the skin, containing serum. A bleb.A pocket of embryonic tissue that is the beginning of an organ.A small cavity formed in volcanic rock by entrapment of a gas bubble during solidification.