lieutenant:
(abbreviation: ‘Lt.‘; plural: ‘lieutenants‘; pronunciation: in British English – the letters ‘lieu’ rhyme with the letters ‘lef’ in “left”; and in American English – the letters ‘lieu’ are said with the sound ‘loo’, as in ‘loop’ — for the different pronunciations of this word, please click here)

Lt. Adam Lamboy, police lieutenant, USA
a person who acts for or takes up the responsibility of some official work in place of someone in a higher position;
an officer of a low rank in the navy, British army, American police, firefighters, etc.,

an underworld don with his lieutenants
The second lieutenant is above the rank of sergeant and below the rank of first lieutenant, and the (first) lieutenant is above the second lieutenant and below the rank of captain, and the lieutenant colonel is above the rank of major and below the rank of colonel.
The title or rank ‘lieutenant’ is used with other positions for various military and police officers; for example, ‘first lieutenant’, ‘lieutenant commander’, ‘lieutenant colonel’, ‘lieutenant governor’ in military; ‘lieutenant officer in the police force; and ‘lieutenant fire-fighter’ in the fire department.
When my uncle was a lieutenant in the Army, I had a very rare opportunity for a civilian to see what life was in the army, especially while getting ready for a major war.
There are lieutenants not only in the Army and Police but also in criminal gangs, underworld criminals and rebels.
