large domain, world

寰 is composed of 宀 (roof) and 睘 (circle). 宀 is a pictograph of a roof, implying coverage, while 睘 means a circle, signifying surrounding or encompassing. Ancient people believed the sky was like a canopy or roof, so 寰 represents the sky and its surroundings, referring to the three-dimensional space we inhabit, the world.