late 13c., from O.Fr. soverain, from V.L. *superanus "chief, principal," from L. super "over" (see super-). Spelling influenced by folk-etymology association with reign. Milton spelled it sovran, as though from It. sovrano. Meaning "gold coin worth 22s 6d" first recorded 1490s; value changed 1817 to 1 pound. As an adj., attested from early 14c.; of remedies or medicines, "potent in a high degree," from late 14c.