People online were amazed to learn what the initials “WC” actually stand for when referring to a toilet.

There are numerous terms for the smallest room in the house, depending on your level of formality. For a polite option, you might use “loo” or “lavatory.” For a more casual or crude term, you might say “crapper” or “sh*tter.”

Regional terms vary as well: in the UK, it’s “khazi,” in Australia, it’s “dunny,” and in the US, it’s “john.” Some might even use the peculiar term “little boys’ room.”

However, the common sign seen on washroom doors is “WC.” What does it mean?

The term “WC” is rooted in history, dating back to a time before modern indoor plumbing. Before indoor plumbing was introduced, there was a separate room for bathing, but it required manually carrying and heating water.

As indoor plumbing became available, there was already a designated room for bathing, so the toilet was placed in a closet, which led to the term “Water Closet”—with “C” standing for closet and “W” for water.

This revelation left many people stunned. One commenter expressed relief at finally learning something they had long wondered about, while another was surprised they had never questioned the meaning before. Some were baffled that anyone could have lived without knowing this, concluding with a reminder to wash your hands.