POTENTATE
dictator, potentate
(noun) a ruler who is unconstrained by law
Source: WordNet® 3.1
Etymology
Noun
potentate (plural potentates)
A powerful leader; a monarch; a ruler.
A powerful polity or institution.
(derogatory) A self-important person.
Usage notes
This term usually carries connotations or implications of ancient despotism before advanced Western conceptions of civil law and Enlightenment values; in other words, a potentate can be described as a king or realm that exercises "raw", absolute power by decree and entrenched in "exotic" customs and traditions (cf. Orientalism). For example, a "Hindu potentate" would refer to those petty kings who controlled various small dominions in India before the British Raj. Particularly in the second sense, use of "potentate" to refer to Western states even before the modern era is rare, and may even be intended humorously in such a case.
Adjective
potentate (comparative more potentate, superlative most potentate)
(obsolete) Regnant, powerful, dominant.
Source: Wiktionary
Po"ten*tate, n. Etym: [LL. potentatus, fr. potentare to exercise
power: cf. F. potentat. See Potent, a.]
Definition: One who is potent; one who possesses great power or sway; a
prince, sovereign, or monarch.
The blessed and only potentate. 1 Tim. vi. 15.
Cherub and seraph, potentates and thrones. Milton.
Source: Webster’s Unabridged Dictionary 1913 Edition