1. The person, body, or state in which independent and supreme authority is vested; especially, in a monarchy, a king, queen, or emperor. No question is to be made but that the bed of the Mississippi belongs to the sovereign, that is, to the nation. (Jefferson)
2. A gold coin of Great Britain, on which an effigy of the head of the reigning king or queen is stamped, valued at one pound sterling, or about $4.86.
3. (Science: zoology) Any butterfly of the tribe Nymphalidi, or genus Basilarchia, as the ursula and the viceroy.
Synonym: king, prince, monarch, potentate, emperor.