n (astronomy) A circular band of coloured light, visible around the sun or moon etc., caused by reflection and refraction of light by ice crystals in the atmosphere.
n (astronomy) A cloud of gas and other matter surrounding and captured by the gravitational field of a large diffuse astronomical object, such as a galaxy or cluster of galaxies.
n (religion) nimbus, a luminous disc, often of gold, around or over the heads of saints, etc., in religious paintings.