source: Code Geass Lelouch Re Surrection Unveils New – Dibujos Para Colorear

1. a supreme ruler, especially a monarch.

｟かたく｠ 君主, 元首〘king, queenなど〙; 主権者, 統治者.

2. a former British gold coin worth one pound sterling, now only minted for commemorative purposes.

ソブリン金貨〘英国の旧1ポンド金貨〙

possessing supreme or ultimate power:

絶対の〈権力など〉; 君主［元首］である

e.g. in modern democracies the people's will is in theory sovereign.

attributive (of a nation or its affairs) acting or done independently and without outside interference:

〖通例名詞の前で〗主権［自治］を有する, 独立した〈国家など〉

e.g. a sovereign, democratic republic

e.g. accusations of interference in sovereign affairs.

attributive archaic or literary possessing royal power and status:

e.g. our most sovereign lord the King.

attributive dated very good or effective:

｟やや古｠ 〖名詞の前で〗卓効［特効］のある〈療法･薬など〉.

e.g. a sovereign remedy for all ills.

sovereignly adverb

Middle English: from Old French soverain, based on Latin super ‘above’. The change in the ending was due to association with reign.