What is the meaning of Lieutenant_colonel?

An army officer in many countries, ranking below a colonel and above a major. Often the commander of a battalion or the executive officer of a regiment.

An English-language term used as a general categorization for military officer ranks that are the equivalent of lieutenant colonel, the relative rank level is found in most countries.

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.

Source: wiktionary.org