The two letters WC, often seen on restroom doors in hotels, airports, restaurants, and other public places, stand for “water closet,” an old English term used to describe a private room containing a toilet. Although the abbreviation may seem unusual today, it has a long history and remains widely recognizable, particularly across Europe.

The history of the modern flush toilet goes back to 1596, when Sir John Harington described an early flushable toilet that used water to remove waste. Nearly two centuries later, in 1775, Alexander Cumming patented an improved design featuring an S-shaped water trap. This important invention helped prevent unpleasant sewer gases from entering buildings through the toilet.

As indoor plumbing and toilets became increasingly common during the 19th century, the expression “water closet” became a familiar way to refer to a toilet room. Over time, the two words were shortened to simply “WC,” creating a convenient label that could be easily understood without requiring a long description or translation.

In the United States, terms such as “bathroom” and “restroom” eventually became much more common in everyday language. In many European countries, however, WC remained a familiar and practical abbreviation and can still be found on signs today. This is why many Americans mainly encounter the letters WC when traveling abroad, where the simple two-letter sign can immediately indicate the location of a toilet.