The option that can be used as a one-word substitute for the given group of words "a room in a public building where outdoor clothes or luggage may be left" is cloakroom.

• Cemetery is a place where dead people are buried.
• Courtyard is an open space surrounded by buildings.
• Hangar is a large building where aircraft are kept.

A cloakroom is a room in a public building where people can leave their outdoor clothes or luggage. Cloakrooms are typically found in places like theaters, museums, and concert halls. Cloakroom attendants are responsible for collecting and storing people's belongings.