"illegal, bad, or dishonest behaviour, especially by people in positions of power"[1]
"Corruption is the dishonest, fraudulent, or criminal use of entrusted authority or power for personal gain or other unlawful or unethical benefits."[2]
Every single aristocracy absolutely fits those definitions. The norm in every aristocracy is to disregard the law in favor of what benefits those in power and to apply the law unequally depending on the desires of rulers.