halo, spread, faint

暈 is composed of 日 (sun) and 軍 (military). 軍 depicts a vehicle wrapped in armor, implying encirclement or attack. Thus, 暈 originally refers to the halo surrounding the sun, later extending to mean diffusion or spreading. Intense sunlight, when stared at for too long, can cause dizziness or blurred vision, so 暈 also carries the meaning of fainting or dizziness.