means The supreme authority of a state or ruler to govern itself without outside interference, holding the final word over its own territory and people.

from From Old French 'soverainete,' built on 'soverain' — the one who sits above all others. That word traces back to Vulgar Latin 'superanus,' from Latin 'super,' meaning 'over' or 'above.' The modern English spelling, with its sneaky 'g,' is a later flourish: it was wrongly nudged toward 'reign' (from Latin 'regnum,' kingdom), as if the word had always been about ruling. It hadn't — the 'g' is a spelling-day intruder, a clerk's flattering misassociation that stuck.