The Oxford Thesaurus An A-Z Dictionary of Synonyms - sovereign n.

1) monarch, ruler, emperor, empress, king, queen, prince, princess, potentate, chief, master, mistress, shah, sultan; Akund (of Swat) , Gaekwar (of Baroda) , Nizam (of Hyderabad) , Mehtar (of Chitral) , Nucifrage of Nuremberg, Sheikh of Araby, Colloq supremo: She is the sovereign and must be obeyed. --adj. 2) supreme, paramount, highest, principal, foremost, greatest, predominant, dominant, ranking, leading, chief, superior, pre-eminent, ruling, regnant, reigning, governing, all-powerful, absolute, unlimited: The first-born of the monarch is vested with sovereign authority upon the monarch's death. 3) royal, regal, majestic, noble, lordly, aristocratic, kingly, queenly: He was hailed as the sovereign ruler of all the islands.