The term 'private compartment' can be summarized as a STATEROOM, which is a nine-letter word. A STATEROOM is a private room on a ship or train, typically one with a bed, used for sleeping and living in. It is usually located in the passenger area of the vessel and is often used by those who are traveling long distances. Staterooms are also commonly found on cruise ships, providing passengers with a comfortable place to rest and relax during their voyage.