Etymology

The rank of lieutenant colonel is often shortened to simply "colonel" in conversation and in unofficial correspondence. Sometimes, the term 'half-colonel' is used in casual conversation in the British Army. Additionally, in the U.S. Army 'light colonel' has been used informally in the past. In the British military, it is customary to refer to either a lieutenant colonel or a colonel by their first names when mentioning them, e.g. "Colonel Tim will be at the parade". In the United States Air Force, the term 'light bird'