Halo is a word with multiple meanings depending on the context:
1. A circle of light shown around or above the head of a sacred figure in religious art
2. The aura of glory or admiration surrounding an idealized person
3. A ring of light around the sun or moon caused by ice crystals in the atmosphere
4. A popular video game franchise developed by Bungie and 343 Industries
5. In medicine, a white ring around the optic nerve seen in glaucoma