- Military.
- a commissioned officer ranking between lieutenant junior grade and lieutenant commander.
- a person who holds an office, civil or military, in subordination to a superior they act for: If he can't attend, he will send his lieutenant.
- a military officer holding commissioned rank immediately junior to a captain
- a naval officer holding commissioned rank immediately junior to a lieutenant commander
- an officer in a police or fire department ranking immediately junior to a captain
- a person who holds an office in subordination to or in place of a superior
