A lieutenant is a rank in the military or police, describing someone who serves as a deputy or assistant to a higher-ranking officer. The word literally means “place holder,” because a lieutenant takes the place of their superior when needed.

In the military, a lieutenant is typically a junior officer who leads small groups of soldiers and learns leadership by working closely with more experienced officers. There are different grades: a second lieutenant is brand new to being an officer, while a first lieutenant has more experience. In the Navy and Coast Guard, a lieutenant is roughly equivalent to an Army captain.

In police departments, a lieutenant usually supervises several sergeants and their teams of officers. They might oversee a particular shift or a specialized unit like the detective squad.

You'll see the word in other contexts too. A ship's captain might have a first mate who serves as their lieutenant, handling day-to-day operations. In some businesses, a trusted assistant who can make decisions in the boss's absence acts as a kind of lieutenant.

The pronunciation is unusual: Americans say “loo-TEN-ant” while the British say “lef-TEN-ant,” one of those quirks of language where two countries pronounce the same word differently.