des·pot 
(dĕspət)
(dĕspət)n.
1. A ruler with absolute power.
2. A person who wields power oppressively; a tyrant.
3.
a. A Byzantine emperor or prince.
b. An Eastern Orthodox bishop or patriarch.
[French despote, from Medieval Latin despota, from Greek despotēs, master; see dem- in the Appendix of Indo-European roots.]
des·potic (dĭ-spŏtĭk) adj.
des·poti·cal·ly adv.