Source : Webster's Revised Unabridged Dictionary (1913)

Vacuole \Vac"u*ole\, n. [L. vacuus empty: cf. F. vacuole.]
   (Biol.)
   A small air cell, or globular space, in the interior of
   organic cells, either containing air, or a pellucid watery
   liquid, or some special chemical secretions of the cell
   protoplasm.

   {Contractile vacuole}. (Zo["o]l.) See under {Contractile},
      and see Illusts. of {Infusoria}, and {Lobosa}.

   {Food vacuole}. (Zo["o]l.) See under {Food}, and see Illust.
      of {Infusoria}.

Source : WordNet®

vacuole
     n : a tiny cavity filled with fluid in the cytoplasm of a cell