first lieutenant 
noun
1A naval officer with executive responsibility for a ship or other command.Piper, made no fewer than 39 patrols as a third hand, first lieutenant and Commanding Officer, in Ursula, Unbeaten and Unsparing....
- It was said, for example, that an engineer four-striper at Sheerness expressed interest, while visiting a submarine, in the business of submerging: he asked the first lieutenant where he got the water from to fill main ballast tanks.
- Today Jacqueline is a graduate and a first lieutenant in the Royal Navy.
1.1A rank of officer in the US army or air force, above second lieutenant and below captain.Michael quickly rose through the ranks as orderly sergeant, first lieutenant and captain....
- He won a theatre award at Bronx Science, and after studying at New York University's old University Heights campus and spending time in the Army as a first lieutenant in the infantry, he set out for Manhattan and the world of the stage.
- Rather than drop out altogether like his fictional creation, however, he persevered in the corps, becoming a first lieutenant and second-in-command of his squadron before his discharge in 1960.