A small, usually fluid-filled, membrane-bound sac within the cytoplasm of a living cell. Vesicles occur, for example, as part of the Golgi apparatus, as lysosomes, or as microbodies. Comparevacuole.
Geology and Earth Sciences
A bubble-shaped cavity in lava, formed by the expansion of entrapped gases. Such cavities may later become filled with material deposited from solution. Vesicular basalt (bubbly basalt lava) is basaltic lava containing numerous openings, generally ellipsoidal or cylindrical in shape, formed by the expansion of dissolved gases in the molten rock. See alsoamygdale; scoriaceous.