Is Capacitor a Unilateral or Bilateral Device?

Da Vinci

Is Capacitor a Unilateral or Bilateral Device ?

Do you mean polarized?
Electrolytic capacitors have anodic oxide coating that works as a dielectric. This is self repairing and will function only when the electrode with the film ( foil or sintered pellet) is positive. If reverse polarized electrolytic action will destroy the dielectric Non electrolytic capacitors (like paper capacitors) have an independent dielectric and are non polarized.