electrolytic capacitor
[ ĭ-lĕk′trə-lĭt′ĭk ]
A type of capacitor in which one plate is coated through electrolysis with an oxide to serve as the dielectric, while the other plate is replaced by an electrolyte. Electrolytic capacitors can achieve very high capacitance with very small sizes, but only act as capacitors as long as the current flows in one direction.