sov·er·eign / ˈsäv(ə)rən/ • n. 1. a supreme ruler, esp. a monarch.2. a former British gold coin worth one pound sterling, now only minted for commemorative purposes.• adj. possessing supreme or ultimate power: in modern democracies the people's will is in theory sovereign. ∎  (of a nation or state) fully independent and determining its own affairs: a sovereign, democratic republic. ∎  (of affairs) subject to a specified state's control without outside interference: criticism was seen as interference in China's sovereign affairs. ∎  archaic or poetic/lit. possessing royal power and status: our most sovereign lord the King. ∎  dated very good or effective: a sovereign remedy for all ills.DERIVATIVES: sov·er·eign·ly adv.

sovereign a supreme ruler, especially a monarch; in early use, applied to God in relation to created things.

From the early 16th century, sovereign also denoted a gold coin, originally, one minted in England from the time of Henry VII to Charles I and at first of the value of 22s. 6d.; later, a British coin worth one pound sterling, now only minted for commemorative purposes.

The word is recorded from Middle English and comes from Old French soverain, based on Latin super ‘above’; the change in ending was due to association with reign.
the sovereign good the greatest good, especially that of a state or its people; the phrase is recorded from Middle English.

sovereign (supreme) ruler XIII; English gold coin of 20 shillings value XVI. ME. soverein — OF. so(u)verain, -ein (mod. souverain) :- Rom. *superānus, f. super above.
Also adj. supreme, paramount. XIV. So sovereignty (-TY2) XIV. — OF. so(u)vereinete (mod. souveraineté).