Many people are just now realizing what the “WC” on restroom signs actually means. In the US, public restrooms have many names—lavatory, restroom, or throne—but “WC” remains a common and often misunderstood label.

A recent discovery on social media has people baffled. “I’m glad someone asked because I’ve been wondering this for years,” one person wrote, while another admitted, “I can’t believe I’ve been living with a WC sign and had no idea why it was called WC.”

So, what does it stand for? The term “WC” actually means “water closet,” a name from the 1900s when toilets were first placed in small closets with running water. As indoor plumbing became more common, the name stuck.

A TikToker explained, “Before indoor plumbing, we actually had a room for the bathtub… Indoor plumbing comes along, and there is already a room with a bath… so where do you put the toilet? Just put it in a closet.”

Now, “WC” refers to a room with a toilet but no bathtub, as confirmed by Plumb World: “WC has been used instead of bathroom to describe a room with a toilet but no bath.”