1. a military officer of middle rank, below captain
Usage: military
2. a police officer ranking below captain
Usage: law enforcement
3. a person who acts as a substitute or assistant to someone in authority

Examples

• The lieutenant led his platoon through the training exercise.
• She was promoted from sergeant to lieutenant last month.
• Lieutenant Johnson reported to the captain immediately.
• The police lieutenant supervised the investigation.
• He served as the governor’s lieutenant during the crisis.
• The lieutenant colonel addressed the troops at dawn.
• She worked as a lieutenant to the department head.