Loo is a British English slang word for a bathroom or toilet. It is also known as the loo-room, lavatory, WC (water closet), lav, can, john, commode, privy, and latrine. Each of these words has its origin and can also have different associations depending on the context it's used in. For example, latrine is a military term, commode might suggest something more old-fashioned, and privy may seem more formal. However, in everyday language, all of these words can be used interchangeably as synonyms for the word loo. In any case, it's always good to have some variation in your vocabulary, especially when it comes to polite and essential nature calls.