Origin

The character combines bamboo (竹) on top with dragon (龍) on the bottom. Bamboo is a natural material used to make baskets and containers, so the bamboo component signals the object itself. The dragon component appears to be used here primarily for its sound value — the character's pronunciations derive from how "dragon" was pronounced. Together, the parts build up the image of a bamboo basket or cage, with the bamboo indicating the material and structure of a container, and the dragon providing phonetic help. Over time, the meaning extended from the physical basket to related ideas like enclosing or confining oneself.