- An army officer in most countries, ranking below a colonel and above a major. Often the commander of a battalion or the executive officer of a regiment.
- An officer in the United States Marine Corps or Royal Marines, of equivalent rank to their counterparts in the army.
- An officer in the United States Air Force, Air Force Reserve, or Air National Guard, ranking below colonel and above major. Often the commander of a squadron or the executive officer of a wing.
When used as a title, it is always capitalized.
- Example: Lieutenant Colonel John Doe.
The rank corresponds to pay grade O-5. Abbreviations: LTC.
- Officer Ranks and Insignia, US Dept. of Defense