Origin

This character combines water on the left with a component meaning big or thick on the right. The image shows water acting on something substantial — washing or filtering through material. Over time, the meaning expanded from the physical act of sieving (separating large from small) to filtering out the unwanted in general, and eventually to ideas of excess or extravagance, since indulgence involves removing restraint. The water radical makes clear this is about a wet process, while the right side suggests something being worked on or transformed.