Both Uses

sovereign
in
The Scarlet Pimpernel
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"How thoughtful of you, Sir Andrew," she said gaily, "surely 'twas your grandmother who taught you that the smell of burnt paper was a sovereign remedy against giddiness."†
Chpt 12 *

Uses with a meaning too rare to warrant foucs:

Men in women's clothes, women in male attire, children disguised in beggars' rags: there were some of all sorts: CI-DEVANT counts, marquises, even dukes, who wanted to fly from France, reach England or some other equally accursed country, and there try to rouse foreign feelings against the glorious Revolution, or to raise an army in order to liberate the wretched prisoners in the Temple, who had once called themselves sovereigns of France.†
Chpt 1 *

Definitions:

(1) (sovereign)
a supreme ruler; or describing a political body as self-governing
(2) (meaning too rare to warrant focus)
a British coin used until 1914; an adjective describing something as powerfully effective