- U.S. Mil. an officer ranking above a second lieutenant and below a captain
- U.S. Navy the officer in charge of maintenance of a ship or shore station
See first lieutenant in American Heritage Dictionary 4
- A commissioned rank in the U.S. Army, Air Force, and Marines that is above second lieutenant and below captain.
- One who holds this rank.
- A lieutenant in the U.S. Navy or Coast Guard, responsible for maintaining the ship's exterior and for management of the ship's deck.
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