A military flag or banner, or a junior naval officer rank just above midshipman.
From Old French 'enseigne' meaning 'sign' or 'badge,' from Latin 'insignia.' Originally referred to the flag that identified a military unit, then extended to the officer who carried it.
An ensign is the lowest commissioned officer rank in many navies, and the title literally comes from the fact that they once carried the ship's flag or 'ensign'—their job was to make sure everyone knew whose ship it was.
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