If you’ve traveled through Europe or parts of Asia, you’ve probably seen the letters “WC” on restroom doors and signs. It simply stands for “water closet,” an old-fashioned English term for a room containing a flush toilet.

The phrase became common in the 19th century, when indoor plumbing was still relatively new. Toilets were often installed in small separate rooms or closets supplied with running water, so people began calling them “water closets.” Over time, the abbreviation WC became a convenient way to label public toilets, hotels, restaurants, train stations, and other facilities.

Interestingly, the term largely disappeared from everyday American English, where people usually say “restroom” or “bathroom.” In Britain, “toilet” became more common in conversation as well. But the abbreviation WC survived internationally because it was short, recognizable, and easy to fit onto signs regardless of language.

You’ll still see WC frequently in countries such as Germany, France, Italy, the Netherlands, Turkey, and across much of Eastern Europe. In many places, people understand the letters even if they don’t actually use the words “water closet” in normal conversation.

So there’s no secret code behind the sign. WC simply means water closet—a traditional name for a toilet or restroom.

It’s one of those everyday abbreviations that millions of people recognize without ever stopping to wonder what the letters actually stand for.